The genetic basis for Gossypium hirsutum race latifolium,the putative ancestor of cultivated upland cotton,emerging from the semi-wild races to be domesticated into cultivated upland cotton is unknown.Here,we reported...The genetic basis for Gossypium hirsutum race latifolium,the putative ancestor of cultivated upland cotton,emerging from the semi-wild races to be domesticated into cultivated upland cotton is unknown.Here,we reported a high-quality genome assembly of G.latifolium.Comparative genome analyses revealed substantial variations in both gene group composition and genomic sequences across 13 cotton genomes,including the expansion of photosynthesis-related gene groups in G.latifolium compared with other races and the pivotal contribution of structural variations(SVs)to G.hirsutum domestication.Based on the resequencing reads and constructed pan-genome of upland cotton,co-selection regions and SVs with significant frequency differences among different populations were identified.Genes located in these regions or affected by these variations may characterize the differences between G.latifolium and other races,and could be involved in maintenance of upland cotton domestication phenotypes.These findings may assist in mining genes for upland cotton improvement and improving the understanding of the genetic basis of upland cotton domestication.展开更多
Background: Cotton fiber yield is a complex trait,which can be influenced by multiple agronomic traits.Unravelling the genetic basis of cotton fiber yield-related traits contributes to genetic improvement of cotton.Re...Background: Cotton fiber yield is a complex trait,which can be influenced by multiple agronomic traits.Unravelling the genetic basis of cotton fiber yield-related traits contributes to genetic improvement of cotton.Results: In this study,503 upland cotton varieties covering the four breeding stages(BS1–BS4,1911–2011)in China were used for association mapping and domestication analysis.One hundred and forty SSR markers significantly associated with ten fiber yield-related traits were identified,among which,29 markers showed an increasing trend contribution to cotton yield-related traits from BS1 to BS4,and 26 markers showed decreased trend effect.Four favorable alleles of 9 major loci(R^(2)≥3)were strongly selected during the breeding stages,and the candidate genes of the four strongly selected alleles were predicated according to the gene function annotation and tissue expression data.Conclusions :The study not only uncovers the genetic basis of 10 cotton yield-related traits but also provides genetic evidence for cotton improvement during the cotton breeding process in China.展开更多
Improving protein quality and grain yield traits coordinately is an important goal for crop breeding.To date,many protein-quality or grain-yield regulation genes have been identified.However,the genetic strategies int...Improving protein quality and grain yield traits coordinately is an important goal for crop breeding.To date,many protein-quality or grain-yield regulation genes have been identified.However,the genetic strategies integrating these genes in good-protein-quality and high-yield crop breeding practice are far from established.Here,we characterized the functions of the MADS domain-containing protein Zm MADS8 and Zea mays G protein gamma subunit 1(Zm GG1)in regulating protein quality and grain yield of maize.Zm MADS8 positively regulates zein protein accumulation and negatively regulates nonzein protein and lysine levels in kernels by interacting with Zm MADS47 to promote the transcriptional activation of Opaque2.Additionally,Zm MADS8 regulates starch content of kernels by targeting genes involved in starch biosynthesis.Zm GG1,a putative interactor of Zm MADS8,negatively regulates kernel number with a trade-off effect on kernel starch accumulation.The mads8;zmgg1 double mutant improved protein quality by attenuating zein biosynthesis and increasing essential lysine level,and increased grain yield by increasing kernel number,compensating for decreased starch biosynthesis.Our findings revealed the biological function of Zm MADS8 and Zm GG1 in regulating protein quality and yield related traits and suggested a genetic strategy by direct editing of Zm MADS8 and Zm GG1 to improve grain yield and protein quality simultaneously.展开更多
Crude fat is an important nutritional component of maize kernels.However,the genetic mechanisms underlying crude fat content in maize kernels remain elusive.Previous studies used single-model genome-wide association s...Crude fat is an important nutritional component of maize kernels.However,the genetic mechanisms underlying crude fat content in maize kernels remain elusive.Previous studies used single-model genome-wide association studies(GWAS)with limited population sizes,which can result in false loci positives and hinder functional gene identification.Therefore,this study used a population consisting of 495 maize inbred lines,combined with 1.25 million single nucleotide polymorphisms(SNPs),and implemented GWAS using six models to identify quantitative trait nucleotides(QTNs)controlling crude fat content and to mine key genes.The results revealed a wide variation in crude fat content(0.62-16.03%)and broad-sense heritability(H^(2))(96.23%).In total,744 significant QTNs were detected,with 147 co-located across different models,environments,and methods.Based on the 147 colocated QTNs,candidate genes were searched at 50 kb up-and down-stream intervals of each QTN.We finally screened eight candidate genes(GRMZM2G169089,GRMZM2G117935,GRMZM2G002075,GRMZM2G368838,GRMZM2G058496,GRMZM2G090669,GRMZM2G001241,and GRMZM2G333454)related to crude fat content that exhibited high expression levels during kernel development in maize inbred line B73.Notably,GRMZM2G169089,GRMZM2G117935,GRMZM2G002075,and GRMZM2G368838 are involved in the linoleic acid metabolic pathway,oil metabolism,kernel growth,and development in maize.Furthermore,co-expression network analysis revealed that the eight candidate genes strongly correlated with 30 known genes.Proteins encoded by candidate genes interact with other proteins and play an important role in oil content and oleic acid metabolism in maize kernels.The best haplotypes of candidate genes might increase crude fat content without decreasing maize yield.These results broaden the understanding of the genetic mechanism of crude fat content and facilitate marker-assisted selection for high-crude fat breeding programs for maize.展开更多
Leaf rust,caused by the fungus Puccinia triticina,is one of the most destructive diseases affecting global wheat production.Developing disease-resistant wheat varieties is the most cost-effective and environmentally f...Leaf rust,caused by the fungus Puccinia triticina,is one of the most destructive diseases affecting global wheat production.Developing disease-resistant wheat varieties is the most cost-effective and environmentally friendly approach to managing this disease.We phenotyped a collection of 559 wheat accessions from five continents for resistance to leaf rust in field trials at three locations in China(Zhoukou,Henan;Wuhan,Hubei;and Xinxiang,Henan)during the 2020–2021,2021–2022,and 2022–2023 cropping seasons,followed by best-linear-unbiased-estimation analysis across environments.These accessions were genotyped using the MGISEQ-2000 re-sequencing platform,and a genome-wide association analysis was subsequently performed.Twenty-four stable leaf rust resistance loci across 15 chromosomes were identified.Among these,11 loci may represent new sources of resistance.Notably,Lr.hzau-2BS.1 and Lr.hzau-7AL were consistently detected across all three environments and BLUE.Lr.hzau-2BS.1 has the highest frequency in European wheat accessions,whereas Lr.hzau-7AL is most prevalent in South American accessions.Gene-expression analysis identified 101 candidate genes associated with these loci.Closely linked Kompetitive Allele Specific PCR(KASP)markers,2B-209172 and 7A-348992,were developed for Lr.hzau-2BS.1 and Lr.hzau-7AL,respectively.Chinese wheat varieties Mianmai 45 and Liaomai 16,which carry resistance alleles at both loci and exhibit<5%leaf rust severity,represent valuable sources of leaf rust resistance for wheat breeding programs.These newly identified resistance loci and their KASP markers provide valuable resource for their exploitation in wheat breeding.展开更多
Re-domestication of diploid potato(Solanum tuberosum)into a seed crop is an innovative breeding method to accelerate genetic improvement.Seed propagation would allow hybrid production and mix superior alleles.However,...Re-domestication of diploid potato(Solanum tuberosum)into a seed crop is an innovative breeding method to accelerate genetic improvement.Seed propagation would allow hybrid production and mix superior alleles.However,almost all diploid potatoes in nature are self-incompatible(SI).Gametophytic self-incompatible(GSI)is a widespread SI in Solanaceae and is controlled by the S locus that contains a ribonuclease(S-RNase)and multiple F-box(SLFs);however,the genetic diversity of the S locus in potato is unclear.This study identified 21 S-RNase alleles involved in SI from 194 diploid potato accessions by large-scale transcriptome sequencing.The levels of amino acid similarity among different S-RNase proteins varied from 31.3 to 95.8%.S2 allele is the most widespread in 194 diploid potatoes and is mainly distributed in the S.tuberosum Group Phureja.Based on genomic annotation and expression analysis,we identified 12 potential functional SI male-determinant genes,S-locus F-box(SLFs),encoding F-box proteins in the S2 locus on a genomic region of approximately 13 Mb.Comparative genomics analysis showed that eight SLF genes are relatively conserved among four homozygous S locus.The Ka and Ks analysis suggested that S-RNase and intra-haplotypic SLF genes have co-evolved.These findings help select suitable pollinators,combine more hybrid combinations,and fully use heterosis to accelerate diploid potato breeding.展开更多
Anthocyanins are a major subclass of flavonoids that have diverse biological functions and benefit human health.In rice(Oryza sativa),the various colors shown by organs are due mainly to the accumulation of anthocyani...Anthocyanins are a major subclass of flavonoids that have diverse biological functions and benefit human health.In rice(Oryza sativa),the various colors shown by organs are due mainly to the accumulation of anthocyanins and are traits associated with domestication.Elucidating the genetic basis of anthocyanin biosynthesis in rice would support the engineering of anthocyanins as well as shedding light on the evolutionary history of O.sativa.We summarize recent progress in rice anthocyanin biosynthesis research,including gene cloning,biosynthetic pathway discovery,and study of the domestication process.We discuss the application of anthocyanin biosynthesis genes in rice breeding.Our object is to broaden knowledge of the genetic basis of anthocyanin biosynthesis in rice and support the breeding of novel rice cultivars.展开更多
Utilization of heterosis has greatly contributed to rice productivity in China and many Asian countries. Superior hybrids usually show heterosis at two stages： canopy development at vegetative stage and panicle devel...Utilization of heterosis has greatly contributed to rice productivity in China and many Asian countries. Superior hybrids usually show heterosis at two stages： canopy development at vegetative stage and panicle development at reproductive stage resulting in heterosis in yield. Although the genetic basis of heterosis in rice has been extensively investigated, all the previous studies focused on yield traits at maturity stage. In this study, we analyzed the genetic basis of heterosis at seedling stage making use of an ＂immortalized F2＂ population composed of 105 hybrids produced by intercrossing recombinant inbred lines （RILs） from a cross between Zhenshan 97 and Minghui 63, the parents of Shanyou 63, which is an elite hybrid widely grown in China. Eight seedling traits, seedling height, tiller number, leaf number, root number, maximum root length, root dry weight, shoot dry weight and total dry weight, were investigated using hydroponic culture. We analyzed single-locus and digenic genetic effects at the whole genome level using an ultrahigh-density SNP bin map obtained by population re-sequencing. The analysis revealed large numbers of heterotic effects for seedling traits including dominance, over- dominance and digenic dominance （epistasis） in both positive and negative directions. Overdominance effects were prevalent for all the traits, and digenic dominance effects also accounted for a large portion of the genetic effects. The results suggested that cumulative small advantages of the single-locus effects and two-locus interactions, most of which could not be detected statistically, could explain the genetic basis of seedling heterosis of the F1 hybrid.展开更多
Yield loss(Y_(Loss)) in the ratoon crop due to crushing damage to left stubble from mechanical harvesting of the main crop is a constraint for wide adoption of mechanized rice ratooning technology.Soil drying before t...Yield loss(Y_(Loss)) in the ratoon crop due to crushing damage to left stubble from mechanical harvesting of the main crop is a constraint for wide adoption of mechanized rice ratooning technology.Soil drying before the harvest of the main crop has been proposed to overcome this problem.The objective of this study was to determine the effect of soil drying during the mid-to-late grain filling stage of the main crop on grain yield of the ratoon crop in a mechanized rice ratooning system.Field experiments were conducted to compare Y_(Loss) between light(LD) and heavy(HD) soil drying treatments in Hubei province,central China in 2017 and 2018.Y_(Loss) was calculated as the percentage of yield reduction in the ratoon crop with the main crop harvested mechanically,relative to the grain yield of the ratoon crop with the main crop harvested manually.In comparison with LD,soil hardness was increased by 42.8%-84.7% in HD at the 5-20 cm soil depth at maturity of the main crop.Soil hardness at 5 and 10 cm depths reached respectively 4.05 and 7.07 kg cm^(-2) in HD.Soil drying treatment did not significantly affect the grain yield of the main crop.Under mechanical harvesting of the main crop,HD increased the grain yield of the ratoon crop by 9.4% relative to LD.Consequently,Y_(Loss) was only 3.4% in HD,in contrast to 16.3% in LD.The differences in grain yield and Y_(Loos) between the two soil drying treatments were explained mainly by panicles m^(-2),which was increased significantly by HD in the track zone of the ratoon crop compared with LD.These results suggest that heavy soil drying practice during the mid-to-late grain filling stage of the main crop is effective for reducing Y_(Loss) of the ratoon crop in a mechanized rice ratooning system.展开更多
Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativ...Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.展开更多
The wide adoption of hybrid rice has greatly increased rice yield in the last several decades.The utilization of heterosis facilitated by male sterility has been a common strategy for hybrid rice development.Here,we s...The wide adoption of hybrid rice has greatly increased rice yield in the last several decades.The utilization of heterosis facilitated by male sterility has been a common strategy for hybrid rice development.Here,we summarize our efforts in the genetic and molecular understanding of heterosis and male sterility together with the related progress from other research groups.Analyses of F1 diallel crosses show that strong heterosis widely exists in hybrids of diverse germplasms,and inter-subspecific hybrids often display higher heterosis.Using the elite hybrid Shanyou 63 as a model,an immortalized F2 population design is conducted for systematic characterization of the biological mechanism of heterosis,with identification of loci controlling heterosis of yield and yield component traits.Dominance,overdominance,and epistasis all play important roles in the genetic basis of heterosis;quantitative assessment of these components well addressed the three classical genetic hypotheses for heterosis.Environment-sensitive genic male sterility(EGMS)enables the development of two-line hybrids,and long noncoding RNAs often function as regulators of EGMS.Inter-subspecific hybrids show greatly reduced fertility;the identification and molecular characterization of hybrid sterility genes offer strategies for overcoming inter-subspecific hybrid sterility.These developments have significant implications for future hybrid rice improvement using genomic breeding.展开更多
Elimination of the CRISPR/Cas9 constructs in edited plants is a prerequisite for assessing genetic stability, conducting phenotypic characterization, and applying for commercialization of the plants. However, removal ...Elimination of the CRISPR/Cas9 constructs in edited plants is a prerequisite for assessing genetic stability, conducting phenotypic characterization, and applying for commercialization of the plants. However, removal of the CRISPR/Cas9 transgenes by genetic segregation and by backcross is laborious and time consuming. We previously reported the development of the transgene killer CRISPR(TKC) technology that uses a pair of suicide genes to trigger self-elimination of the transgenes without compromising gene editing efficiency. The TKC technology enables isolation of transgene-free CRISPR-edited plants within a single generation, greatly accelerating crop improvements. Here, we presented two new TKC vectors that show great efficiency in both editing the target gene and in undergoing self-elimination of the transgenes. The new vectors replaced the CaMV35 S promoter used in our previous TKC vector with two rice promoters to drive one of the suicide genes, providing advantages over our previous TKC vector under certain conditions. The vectors reported here offered more options and flexibility to conduct gene editing experiments in rice.展开更多
Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation o...Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation of combining ability have been produced, and are still extensively used in hybrid breeding. In this review, the genetic basis underlying these breeding strategies is discussed, and a potential genetic control of general combining ability （GCA） is postulated. We suggested that GCA and the yields of inbred lines might be genetically controlled by different sets of loci on the maize genome that are transmitted into offspring. Different inbred lines might possess different favorable alleles for GCA. In hybrids, loci involved in multiple pathways, which are directly or indirectly associated with yield performance, might be regulated by GCA loci. In addition, a case of GCA mapping using a set of testcross progeny from introgression lines is provided.展开更多
In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unc...In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unclear.In this study,three F2 populations are generated from three Yongyou hybrids to determine the genetic basis of the extremely high yield of intersubspecific hybrids.Genome constitution analysis reveals that the female and male parental lines belong to the Geng and Xian subspecies,respectively,although introgression of 20%of the Xian ancestry and 14%of the Geng ancestry are observed.Twenty-five percent of the hybrid genomes carries homozygous Xian or Geng fragments,which harbors hybrid sterility genes such as Sd,Sc,f5,and q S12 and favorable alleles of key yield-related genes,including NAL1,Ghd7,and Ghd8.None of the parents carries the S5+killer of the S5 killer-protector system.Compatible allele combinations of hybrid sterility genes ensure the fertility of these intersubspecific hybrids and overcome the bottleneck in applying intersubspecific hybrids.Additive effects of favorable alleles of yield-related genes fixed in both parents enhances midparent values.Many QTLs for yield and its key component spikelets per panicle shows dominance and the net positive dominant effects lead to heterosis.These factors result in an extremely high yield of the hybrids.These findings will aid in the development of new intersubspecific rice hybrids with diverse genetic backgrounds.展开更多
Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight ...Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight in rice. QTLs were mapped using a BC4F4 population including 192 backcross inbred lines(BILs) derived from a backcross between Xiaolijing(XLJ) and recombinant inbred lines(RILs). The mapping population was planted in both Lingshui(Hainan, 2015) and Fuyang(Zhejiang, 2016), with the short-and long-day conditions, respectively. A total of 10 QTLs for grain length, four for grain width, four for the ratio of grain length to width, and 11 for grain weight were detected in at least one environment and were distributed across 11 chromosomes. The phenotypic variance explained ranged from 6.76–25.68%, 14.30–34.03%, 5.28–26.50%, and 3.01–22.87% for grain length, grain width, the ratio of grain length to width, and thousand grain weight, respectively. Using the sequential residual heterozygotes(SeqRHs) method, qGS7.1, a QTL for grain size and weight, was mapped in a 3.2-Mb interval on chromosome 7. No QTLs about grain size and weight were reported in previous studies in this region, providing a good candidate for functional analysis and breeding utilization.展开更多
The border effect(BE)is widely observed in crop field experiments,and it has been extensively studied in many crops.However,only limited attention has been paid to the BE of ratoon rice.We conducted field experiments ...The border effect(BE)is widely observed in crop field experiments,and it has been extensively studied in many crops.However,only limited attention has been paid to the BE of ratoon rice.We conducted field experiments on ratoon rice in Qichun County,Hubei Province,Central China in 2018 and 2019 to compare the BE in the main and ratoon crops,and to quantify the contribution of BE in the main crop to that in the ratoon crop.The BE of two hybrid varieties was measured for the outermost,second outermost,and third outermost rows in each plot of both crops.To determine the contribution of BE between the two crops,portions of hills in the outermost and second outermost rows were uprooted during the harvest of the main crop so that the second and third outermost rows then became the outermost rows in the ratoon crop.Overall,the BE on grain yield was greater in the main crop than in the ratoon crop.In the main crop,the BE on grain yield was 98.3%in the outermost row,which was explained by the BE on panicles m^(–2),spikelets/panicle,spikelets m^(–2),and total dry weight.In the ratoon crop,the BE on grain yield was reduced to 60.9 and 27.6%with and without the contribution of the BE in the main crop,respectively.Consequently,55.1%of the BE on grain yield in the ratoon crop was contributed from the main crop.High stubble dry weight and non-structural carbohydrate(NSC)accumulation at the harvest of the main crop were responsible for the contribution of BE in the main crop to that in the ratoon crop.Our results suggest that increases in stubble dry weight and NSC accumulation at the harvest of the main crop could be important strategies for developing high-yielding cropping practices in the rice ratooning system.展开更多
A multi-glume （mg） mutant was obtained by screening the T-DNA inserted mutant pool. Anatomical observation revealed that the florets of the mutant showed elongated leafy paleas/lemmas and palea/lemma-like structures...A multi-glume （mg） mutant was obtained by screening the T-DNA inserted mutant pool. Anatomical observation revealed that the florets of the mutant showed elongated leafy paleas/lemmas and palea/lemma-like structures, just like multi-glumes. Among the 215 observed florets of the mutant, 14.27% were failed to produce pistil and stamens, 23.72% showed extra floret generated on the same rachilla, while 62.01% consisted of one to nine stamens and one to three pistils in a single floret. On the other hand, in some cases the transparent bulged vesile-like tissue could be observed at the basis of filament. The mutant showed glumaceous Iodicules, which prevented the florets from opening in natural conditions, while the absolute male and female sterility was an obvious character of the current mutant. Observation on the process of floral organ morphogenesis by a scanning electron microscopy （SEM） indicated that no phenotype difference in floret primordia was found between the wild-type and the mutant. Meanwhile, for the mutant, the beginning of stamen and pistil primordial differentiation was later than the wild type and the palea/lemma-like structure continued to differentiate after the formation of normal palea and lemma. Furthermore, in the mutant the asymmetrical division of floral primordial caused variation in the number of stamens and pistils. Therefore, the genetic analyses indicated that the mutation phenotype was a recessive trait controlled by a single gene and co-segregated with the T-DNA. Based on the phenotypic characteristics, it could be deduced that the mutant was the result of homeotic conversion from the function of the class E genes in ABCD model.展开更多
Shatian pummelo （Citrus grandis L. Osbeck cv. Shatian） is an elite variety in China, and the regeneration of the embryogenic callus is difficult. Diploid Shatian pummelo was used as the female and crossed with the a...Shatian pummelo （Citrus grandis L. Osbeck cv. Shatian） is an elite variety in China, and the regeneration of the embryogenic callus is difficult. Diploid Shatian pummelo was used as the female and crossed with the allotetraploid somatic hybrid NS （Nova Tangelo ＋ Succari Sweet orange）, [ （ C reticulata Blanco x C. paradisi Macf.） cv. Nova ＋ C sinensis L. Osbeck cv. Succari]. About 90 days after pollination, the embryos obtained from crosses were cultured on the solid media of MT ＋ ME （malt extraction, 500 mg L^-1） and MT ＋ GA3 （1 mg L^-1）. The embryogenic callus was initiated from the embryoids and plantlets＇ hypocotyls and could be subcultured. Flow cytometry and SSR analysis verified that the callus was from the triploid hybrids. The callus had embryogenesis capacity and produced a large number of embryoids on MT ＋Lactose （50 g L^-1） medium after being subcultured for two years. It is comparatively easier to obtain the callus from the hybrid embryo than from Shatian pummelo itself. The callus is valuable for the conservation and utilization of Shatian pummelo.展开更多
Xanthomonas bacteria secrete transcription activator-like effector(TALE)proteins into host cells to activate plant disease susceptibility genes to cause disease,and the process is dependent on interaction between bact...Xanthomonas bacteria secrete transcription activator-like effector(TALE)proteins into host cells to activate plant disease susceptibility genes to cause disease,and the process is dependent on interaction between bacteria TFB domain of TALEs and host plant basal transcription factor IIA gamma subunit(TFIIAγ).The key domain or residues of plant TFIIAγand core residues of bacteria TFB domain that are indispensable for TFIIAγ-TALEs interaction in the process of TALE-carrying Xanthomonas invasion plants are unknown.Here,we showed that the thirdα-helix domain of OsTFIIAγ5/Xa5,especially the 38th,39th,40th and 42th residues were key sites for capturing by TALEs of Xanthomonas oryzae pv.oryzae(Xoo),the causal agent of rice bacterial blight disease.The latter segment of Xoo TFB domain harboring seventy-two amino acid residues was vital for TALE specific binding with host plant OsTFIIAγ5/Xa5.Substitution of some residues in this core region of TFB domain completely compromised capacity of TALEs capturing rice OsTFIIAγ5/Xa5.The rich and conserved arginine residues in this core region of TFB domain were responsible for TALE-dependent plant susceptibility gene activation and virulence of Xoo.These results provide a potential strategy for improving resistance to TALE-carrying pathogens in plants by site-specific modification of key residues of host plant TFIIAγ.展开更多
Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant librar...Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant library.At the germination and early seedling stage,the mutant plants were indistinguishable from the normal ones.However,all of the plant organs were brittle after the 5th-leaf stage and remained brittle throughout the rest of the growing period.Microstructure observation showed that the cell wall in vascular bundle sheath of Bk-x was thinner than that in normal plants.The leaf mechanical strength in Bk-x was 77.9% of that in normal plants growing at Xishuangbanna（BN）,Yunnan province and that was 61.7% in Wuhan（WH）,Hubei Province,China.The proportion of cellulose was 12.3% in Bk-x,which was significantly lower than that in normal plants（26.7%）,while the soluble sugar content was 36.1% in Bk-x,which is significantly higher than that in normal plants（12.4%）.Genetic analysis using two F 2 populations and one F 2：3 families demonstrated that the trait of brittle stalk is controlled by a single recessive gene.展开更多
基金supported by the National Natural Science Foundation of China(32201873)the Key Research and Development Plan of Hubei Province(2023BBB050)。
文摘The genetic basis for Gossypium hirsutum race latifolium,the putative ancestor of cultivated upland cotton,emerging from the semi-wild races to be domesticated into cultivated upland cotton is unknown.Here,we reported a high-quality genome assembly of G.latifolium.Comparative genome analyses revealed substantial variations in both gene group composition and genomic sequences across 13 cotton genomes,including the expansion of photosynthesis-related gene groups in G.latifolium compared with other races and the pivotal contribution of structural variations(SVs)to G.hirsutum domestication.Based on the resequencing reads and constructed pan-genome of upland cotton,co-selection regions and SVs with significant frequency differences among different populations were identified.Genes located in these regions or affected by these variations may characterize the differences between G.latifolium and other races,and could be involved in maintenance of upland cotton domestication phenotypes.These findings may assist in mining genes for upland cotton improvement and improving the understanding of the genetic basis of upland cotton domestication.
基金This work was supported by the National Natural Science Foundation of China(31760402)Young and Middle-aged Science and Technology Leading Talents of Xinjiang Production and Construction Corps(2019CB027).
文摘Background: Cotton fiber yield is a complex trait,which can be influenced by multiple agronomic traits.Unravelling the genetic basis of cotton fiber yield-related traits contributes to genetic improvement of cotton.Results: In this study,503 upland cotton varieties covering the four breeding stages(BS1–BS4,1911–2011)in China were used for association mapping and domestication analysis.One hundred and forty SSR markers significantly associated with ten fiber yield-related traits were identified,among which,29 markers showed an increasing trend contribution to cotton yield-related traits from BS1 to BS4,and 26 markers showed decreased trend effect.Four favorable alleles of 9 major loci(R^(2)≥3)were strongly selected during the breeding stages,and the candidate genes of the four strongly selected alleles were predicated according to the gene function annotation and tissue expression data.Conclusions :The study not only uncovers the genetic basis of 10 cotton yield-related traits but also provides genetic evidence for cotton improvement during the cotton breeding process in China.
基金supported by the Biological Breeding-National Science and Technology Major Project(2023ZD0406804,2023ZD0402701)Major Project of Hubei Hongshan Laboratory(2022hszd019)First-Class Discipline Construction Funds of the College of Plant Science and Technology at Huazhong Agricultural University(2022ZK PY002)。
文摘Improving protein quality and grain yield traits coordinately is an important goal for crop breeding.To date,many protein-quality or grain-yield regulation genes have been identified.However,the genetic strategies integrating these genes in good-protein-quality and high-yield crop breeding practice are far from established.Here,we characterized the functions of the MADS domain-containing protein Zm MADS8 and Zea mays G protein gamma subunit 1(Zm GG1)in regulating protein quality and grain yield of maize.Zm MADS8 positively regulates zein protein accumulation and negatively regulates nonzein protein and lysine levels in kernels by interacting with Zm MADS47 to promote the transcriptional activation of Opaque2.Additionally,Zm MADS8 regulates starch content of kernels by targeting genes involved in starch biosynthesis.Zm GG1,a putative interactor of Zm MADS8,negatively regulates kernel number with a trade-off effect on kernel starch accumulation.The mads8;zmgg1 double mutant improved protein quality by attenuating zein biosynthesis and increasing essential lysine level,and increased grain yield by increasing kernel number,compensating for decreased starch biosynthesis.Our findings revealed the biological function of Zm MADS8 and Zm GG1 in regulating protein quality and yield related traits and suggested a genetic strategy by direct editing of Zm MADS8 and Zm GG1 to improve grain yield and protein quality simultaneously.
基金supported by the National Natural Science Foundation of China(32101700)the China Postdoctoral Science Foundation(2022M7111220)+1 种基金the Science and Technology Innovation Program of Hunan Province,China(2021RC2082)and the Postgraduate Scientific Research Innovation Project of Hunan Province,China(CX20230697)。
文摘Crude fat is an important nutritional component of maize kernels.However,the genetic mechanisms underlying crude fat content in maize kernels remain elusive.Previous studies used single-model genome-wide association studies(GWAS)with limited population sizes,which can result in false loci positives and hinder functional gene identification.Therefore,this study used a population consisting of 495 maize inbred lines,combined with 1.25 million single nucleotide polymorphisms(SNPs),and implemented GWAS using six models to identify quantitative trait nucleotides(QTNs)controlling crude fat content and to mine key genes.The results revealed a wide variation in crude fat content(0.62-16.03%)and broad-sense heritability(H^(2))(96.23%).In total,744 significant QTNs were detected,with 147 co-located across different models,environments,and methods.Based on the 147 colocated QTNs,candidate genes were searched at 50 kb up-and down-stream intervals of each QTN.We finally screened eight candidate genes(GRMZM2G169089,GRMZM2G117935,GRMZM2G002075,GRMZM2G368838,GRMZM2G058496,GRMZM2G090669,GRMZM2G001241,and GRMZM2G333454)related to crude fat content that exhibited high expression levels during kernel development in maize inbred line B73.Notably,GRMZM2G169089,GRMZM2G117935,GRMZM2G002075,and GRMZM2G368838 are involved in the linoleic acid metabolic pathway,oil metabolism,kernel growth,and development in maize.Furthermore,co-expression network analysis revealed that the eight candidate genes strongly correlated with 30 known genes.Proteins encoded by candidate genes interact with other proteins and play an important role in oil content and oleic acid metabolism in maize kernels.The best haplotypes of candidate genes might increase crude fat content without decreasing maize yield.These results broaden the understanding of the genetic mechanism of crude fat content and facilitate marker-assisted selection for high-crude fat breeding programs for maize.
基金supported by the National Key Research and Development Program of China(2022YFD1201300,2022YFD1201500)Biological Breeding-National Science and Technology Major Project(2023ZD04025)+1 种基金National Natural Science Foundation of China(W2412009,32372173,32101779,32260485)the Hubei Hongshan Laboratory(2022hspy001,2021hskf008,and 2022hspy010).
文摘Leaf rust,caused by the fungus Puccinia triticina,is one of the most destructive diseases affecting global wheat production.Developing disease-resistant wheat varieties is the most cost-effective and environmentally friendly approach to managing this disease.We phenotyped a collection of 559 wheat accessions from five continents for resistance to leaf rust in field trials at three locations in China(Zhoukou,Henan;Wuhan,Hubei;and Xinxiang,Henan)during the 2020–2021,2021–2022,and 2022–2023 cropping seasons,followed by best-linear-unbiased-estimation analysis across environments.These accessions were genotyped using the MGISEQ-2000 re-sequencing platform,and a genome-wide association analysis was subsequently performed.Twenty-four stable leaf rust resistance loci across 15 chromosomes were identified.Among these,11 loci may represent new sources of resistance.Notably,Lr.hzau-2BS.1 and Lr.hzau-7AL were consistently detected across all three environments and BLUE.Lr.hzau-2BS.1 has the highest frequency in European wheat accessions,whereas Lr.hzau-7AL is most prevalent in South American accessions.Gene-expression analysis identified 101 candidate genes associated with these loci.Closely linked Kompetitive Allele Specific PCR(KASP)markers,2B-209172 and 7A-348992,were developed for Lr.hzau-2BS.1 and Lr.hzau-7AL,respectively.Chinese wheat varieties Mianmai 45 and Liaomai 16,which carry resistance alleles at both loci and exhibit<5%leaf rust severity,represent valuable sources of leaf rust resistance for wheat breeding programs.These newly identified resistance loci and their KASP markers provide valuable resource for their exploitation in wheat breeding.
基金supported by the National Natural Science Foundation of China(32372695 and 32488302)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(CAASZDRW202404)。
文摘Re-domestication of diploid potato(Solanum tuberosum)into a seed crop is an innovative breeding method to accelerate genetic improvement.Seed propagation would allow hybrid production and mix superior alleles.However,almost all diploid potatoes in nature are self-incompatible(SI).Gametophytic self-incompatible(GSI)is a widespread SI in Solanaceae and is controlled by the S locus that contains a ribonuclease(S-RNase)and multiple F-box(SLFs);however,the genetic diversity of the S locus in potato is unclear.This study identified 21 S-RNase alleles involved in SI from 194 diploid potato accessions by large-scale transcriptome sequencing.The levels of amino acid similarity among different S-RNase proteins varied from 31.3 to 95.8%.S2 allele is the most widespread in 194 diploid potatoes and is mainly distributed in the S.tuberosum Group Phureja.Based on genomic annotation and expression analysis,we identified 12 potential functional SI male-determinant genes,S-locus F-box(SLFs),encoding F-box proteins in the S2 locus on a genomic region of approximately 13 Mb.Comparative genomics analysis showed that eight SLF genes are relatively conserved among four homozygous S locus.The Ka and Ks analysis suggested that S-RNase and intra-haplotypic SLF genes have co-evolved.These findings help select suitable pollinators,combine more hybrid combinations,and fully use heterosis to accelerate diploid potato breeding.
基金supported by the National Program on R&D of Transgenic Plants(2016ZX08009003-004)the National Natural Science Foundation of China(91935303,32001530)+1 种基金the China Agriculture Research System(CARS-01-03)the Postdoctoral Science Foundation of China(2020M682441)。
文摘Anthocyanins are a major subclass of flavonoids that have diverse biological functions and benefit human health.In rice(Oryza sativa),the various colors shown by organs are due mainly to the accumulation of anthocyanins and are traits associated with domestication.Elucidating the genetic basis of anthocyanin biosynthesis in rice would support the engineering of anthocyanins as well as shedding light on the evolutionary history of O.sativa.We summarize recent progress in rice anthocyanin biosynthesis research,including gene cloning,biosynthetic pathway discovery,and study of the domestication process.We discuss the application of anthocyanin biosynthesis genes in rice breeding.Our object is to broaden knowledge of the genetic basis of anthocyanin biosynthesis in rice and support the breeding of novel rice cultivars.
基金supported by grants from the National Natural Science Foundation of China(No.31330039)National 863 Project(No.2014AA10A604)the Bill&Melinda Gates Foundation(No.OPP51587)
文摘Utilization of heterosis has greatly contributed to rice productivity in China and many Asian countries. Superior hybrids usually show heterosis at two stages： canopy development at vegetative stage and panicle development at reproductive stage resulting in heterosis in yield. Although the genetic basis of heterosis in rice has been extensively investigated, all the previous studies focused on yield traits at maturity stage. In this study, we analyzed the genetic basis of heterosis at seedling stage making use of an ＂immortalized F2＂ population composed of 105 hybrids produced by intercrossing recombinant inbred lines （RILs） from a cross between Zhenshan 97 and Minghui 63, the parents of Shanyou 63, which is an elite hybrid widely grown in China. Eight seedling traits, seedling height, tiller number, leaf number, root number, maximum root length, root dry weight, shoot dry weight and total dry weight, were investigated using hydroponic culture. We analyzed single-locus and digenic genetic effects at the whole genome level using an ultrahigh-density SNP bin map obtained by population re-sequencing. The analysis revealed large numbers of heterotic effects for seedling traits including dominance, over- dominance and digenic dominance （epistasis） in both positive and negative directions. Overdominance effects were prevalent for all the traits, and digenic dominance effects also accounted for a large portion of the genetic effects. The results suggested that cumulative small advantages of the single-locus effects and two-locus interactions, most of which could not be detected statistically, could explain the genetic basis of seedling heterosis of the F1 hybrid.
基金supported by the Major International (Regional)Joint Research Project of National Natural Science Foundation of China (32061143038)the China Agriculture Research System(CARS-01-20)the Fundamental Research Funds for the Central Universities (2662020ZKPY015)。
文摘Yield loss(Y_(Loss)) in the ratoon crop due to crushing damage to left stubble from mechanical harvesting of the main crop is a constraint for wide adoption of mechanized rice ratooning technology.Soil drying before the harvest of the main crop has been proposed to overcome this problem.The objective of this study was to determine the effect of soil drying during the mid-to-late grain filling stage of the main crop on grain yield of the ratoon crop in a mechanized rice ratooning system.Field experiments were conducted to compare Y_(Loss) between light(LD) and heavy(HD) soil drying treatments in Hubei province,central China in 2017 and 2018.Y_(Loss) was calculated as the percentage of yield reduction in the ratoon crop with the main crop harvested mechanically,relative to the grain yield of the ratoon crop with the main crop harvested manually.In comparison with LD,soil hardness was increased by 42.8%-84.7% in HD at the 5-20 cm soil depth at maturity of the main crop.Soil hardness at 5 and 10 cm depths reached respectively 4.05 and 7.07 kg cm^(-2) in HD.Soil drying treatment did not significantly affect the grain yield of the main crop.Under mechanical harvesting of the main crop,HD increased the grain yield of the ratoon crop by 9.4% relative to LD.Consequently,Y_(Loss) was only 3.4% in HD,in contrast to 16.3% in LD.The differences in grain yield and Y_(Loos) between the two soil drying treatments were explained mainly by panicles m^(-2),which was increased significantly by HD in the track zone of the ratoon crop compared with LD.These results suggest that heavy soil drying practice during the mid-to-late grain filling stage of the main crop is effective for reducing Y_(Loss) of the ratoon crop in a mechanized rice ratooning system.
文摘Ratoon rice cropping is an important component of the rice cropping system in Texas and south Louisiana,USA,and expanded to Asian countries in 1970.Two field studies were conducted with widely planted rice(Oryza sativa L.)cultivars at Eagle Lake,Texas,USA to determine the effects of nitrogen(N)management in main(first)crop(MC)and ratoon(second)crop(RC)on RC yield.In 2012 and 2013,one cultivar(Presidio)was adopted to determine the effects of RC N management on ratoon yield and head rice yield.In 2016 and 2017,CL153,CL163 and CL272 in addition to Presidio were adopted to examine the effect of MC N management on ratoon yield and head rice yield.N applied at preflood after MC harvest considerably improved RC yield.Application of 99 kg N ha^(–1)at preflood after MC harvest was practically adequate for RC regrowth,development and approaching the yield potential for Presidio.RC could produce quite high average grain yields of 5.90 to 6.53 t ha–1 in 2012 and 2013,respectively.Main crop N rate only significantly affected MC yield;however,given N applied of 99 kg ha^(–1)at preflood after MC harvest,ratoon yield was not significantly affected by MC N rate.Neither the main nor ratoon crop N management had a significant effect on RC head rice yield.Considerable RC head rice yields(55–65%)were observed in all of the four cultivars and 4 years except for CL272 in 2016.These results indicat that without very high N fertilizer application,rice ratoon crop could produce a considerable grain yield and an expectative head rice yield.Rice ratooning could be a practical way to increase rice yields with the minimal input in south Texas and regions with a similar climate.
基金supported by grants from the National Natural Science Foundation of China (31991223, 32170622 and 31821005)the Natural Science Foundation of Hubei Province (2019CFA061)the Fundamental Research Funds for the Central Universities (2662020SKPY005)
文摘The wide adoption of hybrid rice has greatly increased rice yield in the last several decades.The utilization of heterosis facilitated by male sterility has been a common strategy for hybrid rice development.Here,we summarize our efforts in the genetic and molecular understanding of heterosis and male sterility together with the related progress from other research groups.Analyses of F1 diallel crosses show that strong heterosis widely exists in hybrids of diverse germplasms,and inter-subspecific hybrids often display higher heterosis.Using the elite hybrid Shanyou 63 as a model,an immortalized F2 population design is conducted for systematic characterization of the biological mechanism of heterosis,with identification of loci controlling heterosis of yield and yield component traits.Dominance,overdominance,and epistasis all play important roles in the genetic basis of heterosis;quantitative assessment of these components well addressed the three classical genetic hypotheses for heterosis.Environment-sensitive genic male sterility(EGMS)enables the development of two-line hybrids,and long noncoding RNAs often function as regulators of EGMS.Inter-subspecific hybrids show greatly reduced fertility;the identification and molecular characterization of hybrid sterility genes offer strategies for overcoming inter-subspecific hybrid sterility.These developments have significant implications for future hybrid rice improvement using genomic breeding.
基金supported by Chinese Ministry of Agriculture and Rural Affairs (Grant No. 2018ZX0801003B)the National Transgenic Science and Technology Program (Grant No. 2016ZX08010002)
文摘Elimination of the CRISPR/Cas9 constructs in edited plants is a prerequisite for assessing genetic stability, conducting phenotypic characterization, and applying for commercialization of the plants. However, removal of the CRISPR/Cas9 transgenes by genetic segregation and by backcross is laborious and time consuming. We previously reported the development of the transgene killer CRISPR(TKC) technology that uses a pair of suicide genes to trigger self-elimination of the transgenes without compromising gene editing efficiency. The TKC technology enables isolation of transgene-free CRISPR-edited plants within a single generation, greatly accelerating crop improvements. Here, we presented two new TKC vectors that show great efficiency in both editing the target gene and in undergoing self-elimination of the transgenes. The new vectors replaced the CaMV35 S promoter used in our previous TKC vector with two rice promoters to drive one of the suicide genes, providing advantages over our previous TKC vector under certain conditions. The vectors reported here offered more options and flexibility to conduct gene editing experiments in rice.
基金supported by the National Basic Research Program of China (2011CB100100)the National Natural Science Foundation of China (30971791)
文摘Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation of combining ability have been produced, and are still extensively used in hybrid breeding. In this review, the genetic basis underlying these breeding strategies is discussed, and a potential genetic control of general combining ability （GCA） is postulated. We suggested that GCA and the yields of inbred lines might be genetically controlled by different sets of loci on the maize genome that are transmitted into offspring. Different inbred lines might possess different favorable alleles for GCA. In hybrids, loci involved in multiple pathways, which are directly or indirectly associated with yield performance, might be regulated by GCA loci. In addition, a case of GCA mapping using a set of testcross progeny from introgression lines is provided.
基金partially supported by funds from the National Natural Science Foundation of China (32061143042, 31821005, 91935302)The National Key Research and Development Program of China(2016YFD0100802)
文摘In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unclear.In this study,three F2 populations are generated from three Yongyou hybrids to determine the genetic basis of the extremely high yield of intersubspecific hybrids.Genome constitution analysis reveals that the female and male parental lines belong to the Geng and Xian subspecies,respectively,although introgression of 20%of the Xian ancestry and 14%of the Geng ancestry are observed.Twenty-five percent of the hybrid genomes carries homozygous Xian or Geng fragments,which harbors hybrid sterility genes such as Sd,Sc,f5,and q S12 and favorable alleles of key yield-related genes,including NAL1,Ghd7,and Ghd8.None of the parents carries the S5+killer of the S5 killer-protector system.Compatible allele combinations of hybrid sterility genes ensure the fertility of these intersubspecific hybrids and overcome the bottleneck in applying intersubspecific hybrids.Additive effects of favorable alleles of yield-related genes fixed in both parents enhances midparent values.Many QTLs for yield and its key component spikelets per panicle shows dominance and the net positive dominant effects lead to heterosis.These factors result in an extremely high yield of the hybrids.These findings will aid in the development of new intersubspecific rice hybrids with diverse genetic backgrounds.
基金supported by grants from the National Key Research and Development Program of China (2018YFD0100806)the Zhejiang Provincial Natural Science Foundation of China (LY18C130008)+2 种基金the National Natural Science Foundation of China (31521064)the Major Project of the Genetically Modified and National Key Transgenic Research Projects, China (2016ZX08001-002)the Super Rice Breeding Innovation Team and Rice Heterosis Mechanism Research Innovation Team of the Chinese Academy of Agricultural Sciences Innovation Project (CAASASTIP-2013-CNRRI)
文摘Grain size is a major determinant of grain weight, which is one of the components of rice yield. The objective o this study was to identify novel, and important quantitative trait loci(QTLs) for grain size and weight in rice. QTLs were mapped using a BC4F4 population including 192 backcross inbred lines(BILs) derived from a backcross between Xiaolijing(XLJ) and recombinant inbred lines(RILs). The mapping population was planted in both Lingshui(Hainan, 2015) and Fuyang(Zhejiang, 2016), with the short-and long-day conditions, respectively. A total of 10 QTLs for grain length, four for grain width, four for the ratio of grain length to width, and 11 for grain weight were detected in at least one environment and were distributed across 11 chromosomes. The phenotypic variance explained ranged from 6.76–25.68%, 14.30–34.03%, 5.28–26.50%, and 3.01–22.87% for grain length, grain width, the ratio of grain length to width, and thousand grain weight, respectively. Using the sequential residual heterozygotes(SeqRHs) method, qGS7.1, a QTL for grain size and weight, was mapped in a 3.2-Mb interval on chromosome 7. No QTLs about grain size and weight were reported in previous studies in this region, providing a good candidate for functional analysis and breeding utilization.
基金supported by the Major International(Regional)Joint Research Project of National Natural Science Foundation of China(32061143038)the earmarked fund for China Agriculture Research System(CARS-01-20)+1 种基金the National High Technology Research and Development Program of China(the 863 Project,2014AA10A605)the Fundamental Research Funds for the Central Universities,China(2662020ZKPY015).
文摘The border effect(BE)is widely observed in crop field experiments,and it has been extensively studied in many crops.However,only limited attention has been paid to the BE of ratoon rice.We conducted field experiments on ratoon rice in Qichun County,Hubei Province,Central China in 2018 and 2019 to compare the BE in the main and ratoon crops,and to quantify the contribution of BE in the main crop to that in the ratoon crop.The BE of two hybrid varieties was measured for the outermost,second outermost,and third outermost rows in each plot of both crops.To determine the contribution of BE between the two crops,portions of hills in the outermost and second outermost rows were uprooted during the harvest of the main crop so that the second and third outermost rows then became the outermost rows in the ratoon crop.Overall,the BE on grain yield was greater in the main crop than in the ratoon crop.In the main crop,the BE on grain yield was 98.3%in the outermost row,which was explained by the BE on panicles m^(–2),spikelets/panicle,spikelets m^(–2),and total dry weight.In the ratoon crop,the BE on grain yield was reduced to 60.9 and 27.6%with and without the contribution of the BE in the main crop,respectively.Consequently,55.1%of the BE on grain yield in the ratoon crop was contributed from the main crop.High stubble dry weight and non-structural carbohydrate(NSC)accumulation at the harvest of the main crop were responsible for the contribution of BE in the main crop to that in the ratoon crop.Our results suggest that increases in stubble dry weight and NSC accumulation at the harvest of the main crop could be important strategies for developing high-yielding cropping practices in the rice ratooning system.
文摘A multi-glume （mg） mutant was obtained by screening the T-DNA inserted mutant pool. Anatomical observation revealed that the florets of the mutant showed elongated leafy paleas/lemmas and palea/lemma-like structures, just like multi-glumes. Among the 215 observed florets of the mutant, 14.27% were failed to produce pistil and stamens, 23.72% showed extra floret generated on the same rachilla, while 62.01% consisted of one to nine stamens and one to three pistils in a single floret. On the other hand, in some cases the transparent bulged vesile-like tissue could be observed at the basis of filament. The mutant showed glumaceous Iodicules, which prevented the florets from opening in natural conditions, while the absolute male and female sterility was an obvious character of the current mutant. Observation on the process of floral organ morphogenesis by a scanning electron microscopy （SEM） indicated that no phenotype difference in floret primordia was found between the wild-type and the mutant. Meanwhile, for the mutant, the beginning of stamen and pistil primordial differentiation was later than the wild type and the palea/lemma-like structure continued to differentiate after the formation of normal palea and lemma. Furthermore, in the mutant the asymmetrical division of floral primordial caused variation in the number of stamens and pistils. Therefore, the genetic analyses indicated that the mutation phenotype was a recessive trait controlled by a single gene and co-segregated with the T-DNA. Based on the phenotypic characteristics, it could be deduced that the mutant was the result of homeotic conversion from the function of the class E genes in ABCD model.
基金This work was financially supported by the National Natural Science Foundation of China （30570973）Ministry of Science ＆ Technology, and Ministry of Education （IRT0548）.
文摘Shatian pummelo （Citrus grandis L. Osbeck cv. Shatian） is an elite variety in China, and the regeneration of the embryogenic callus is difficult. Diploid Shatian pummelo was used as the female and crossed with the allotetraploid somatic hybrid NS （Nova Tangelo ＋ Succari Sweet orange）, [ （ C reticulata Blanco x C. paradisi Macf.） cv. Nova ＋ C sinensis L. Osbeck cv. Succari]. About 90 days after pollination, the embryos obtained from crosses were cultured on the solid media of MT ＋ ME （malt extraction, 500 mg L^-1） and MT ＋ GA3 （1 mg L^-1）. The embryogenic callus was initiated from the embryoids and plantlets＇ hypocotyls and could be subcultured. Flow cytometry and SSR analysis verified that the callus was from the triploid hybrids. The callus had embryogenesis capacity and produced a large number of embryoids on MT ＋Lactose （50 g L^-1） medium after being subcultured for two years. It is comparatively easier to obtain the callus from the hybrid embryo than from Shatian pummelo itself. The callus is valuable for the conservation and utilization of Shatian pummelo.
基金supported by the grants from the National Natural Science Foundation of China (31822042 and 31871946)the Fundamental Research Funds for the Central Universities, China (2662016PY020 and 2662017PY014)
文摘Xanthomonas bacteria secrete transcription activator-like effector(TALE)proteins into host cells to activate plant disease susceptibility genes to cause disease,and the process is dependent on interaction between bacteria TFB domain of TALEs and host plant basal transcription factor IIA gamma subunit(TFIIAγ).The key domain or residues of plant TFIIAγand core residues of bacteria TFB domain that are indispensable for TFIIAγ-TALEs interaction in the process of TALE-carrying Xanthomonas invasion plants are unknown.Here,we showed that the thirdα-helix domain of OsTFIIAγ5/Xa5,especially the 38th,39th,40th and 42th residues were key sites for capturing by TALEs of Xanthomonas oryzae pv.oryzae(Xoo),the causal agent of rice bacterial blight disease.The latter segment of Xoo TFB domain harboring seventy-two amino acid residues was vital for TALE specific binding with host plant OsTFIIAγ5/Xa5.Substitution of some residues in this core region of TFB domain completely compromised capacity of TALEs capturing rice OsTFIIAγ5/Xa5.The rich and conserved arginine residues in this core region of TFB domain were responsible for TALE-dependent plant susceptibility gene activation and virulence of Xoo.These results provide a potential strategy for improving resistance to TALE-carrying pathogens in plants by site-specific modification of key residues of host plant TFIIAγ.
基金supported by the National High-Tech R&D Program of China(2006AA10A106)
文摘Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant library.At the germination and early seedling stage,the mutant plants were indistinguishable from the normal ones.However,all of the plant organs were brittle after the 5th-leaf stage and remained brittle throughout the rest of the growing period.Microstructure observation showed that the cell wall in vascular bundle sheath of Bk-x was thinner than that in normal plants.The leaf mechanical strength in Bk-x was 77.9% of that in normal plants growing at Xishuangbanna（BN）,Yunnan province and that was 61.7% in Wuhan（WH）,Hubei Province,China.The proportion of cellulose was 12.3% in Bk-x,which was significantly lower than that in normal plants（26.7%）,while the soluble sugar content was 36.1% in Bk-x,which is significantly higher than that in normal plants（12.4%）.Genetic analysis using two F 2 populations and one F 2：3 families demonstrated that the trait of brittle stalk is controlled by a single recessive gene.
