The cucumber(Cucumis sativus L.)is an important vegetable crop worldwide,and fruit trichomes or spines are an important trait for external fruit quality.The mechanisms underlying spine formation are not well understoo...The cucumber(Cucumis sativus L.)is an important vegetable crop worldwide,and fruit trichomes or spines are an important trait for external fruit quality.The mechanisms underlying spine formation are not well understood,but the plant-specific NAC family of transcription factors may play important roles in fruit spine initiation and development.In this study,we conducted a genome-wide survey and identified 91 NAC gene homologs in the cucumber genome.Clustering analysis classified these genes into six subfamilies;each contained a varying number of NAC family members with a similar intron–exon structure and conserved motifs.Quantitative real-time PCR analysis revealed tissue-specific expression patterns of these genes,including 10 and 12 that exhibited preferential expression in the stem and fruit,respectively.Thirteen of the 91 NAC genes showed higher expression in the wild-type plant than in its near-isogenic trichome mutant,suggesting their important roles in fruit spine development.Exogenous application of four plant hormones promoted spine formation and increased spine density on the cucumber fruits;several NAC genes showed differential expression over time in response to phytohormone treatments on cucumber fruit,implying their essential roles in fruit-trichome development.Among the NAC genes identified,12 were found to be targets of 13 known cucumber micro-RNAs.Collectively,these findings provide a useful resource for further analysis of the interactions between NAC genes and genes underlying trichome organogenesis and development during fruit spine development in cucumber.展开更多
Dwarfism is an important plant architecture trait in crop breeding（Peng et al.,1999;Sasaki el al.,2002）.In cucurbits.the compact plant type was proposed to develop new varieties for the once-over mechanical harvest ...Dwarfism is an important plant architecture trait in crop breeding（Peng et al.,1999;Sasaki el al.,2002）.In cucurbits.the compact plant type was proposed to develop new varieties for the once-over mechanical harvest for concentrated fruit set and higher densities（Li et al.,2011;Mondal et al.,2011）.展开更多
In plants,WUSCHEL-related homeobox1(WOX1)homologs promote lamina mediolateral outgrowth.However,the downstream components linking WOX1 and lamina development remain unclear.In this study,we revealed the roles of WOX1 ...In plants,WUSCHEL-related homeobox1(WOX1)homologs promote lamina mediolateral outgrowth.However,the downstream components linking WOX1 and lamina development remain unclear.In this study,we revealed the roles of WOX1 in palmate leaf expansion in cucumber(Cucumis sativus).A cucumber mango fruit(mf)mutant,resulting from truncation of a WOX1-type protein(CsWOX1),displayed abnormal lamina growth and defects in the development of secondary and smaller veins.CsWOX1 was expressed in the middle mesophyll and leaf margins and rescued defects of the Arabidopsis wox1 prs double mutant.Transcriptomic analysis revealed that genes involved in auxin polar transport and auxin response were highly associated with leaf development.Analysis of the cucumber mf rl(round leaf)double mutant revealed that CsWOX1 functioned in vein development via PINOID(CsPID1)-controlled auxin transport.Overexpression of CsWOX1 in cucumber(CsWOX1-OE)affected vein patterning and produced‘butterfly-shaped’leaves.CsWOX1 physically interacted with CsTCP4a,which may account for the abnormal lamina development in the mf mutant line and the smaller leaves in the CsWOX1-OE plants.Our findings demonstrated that CsWOX1 regulates cucumber leaf vein development by modulating auxin polar transport;moreover,CsWOX1 regulates leaf size by controlling CIN-TCP genes.展开更多
Plant height is one of the most important agronomic traits that directly determines plant architecture,and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lod...Plant height is one of the most important agronomic traits that directly determines plant architecture,and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lodging resistance and economic yield.At least four dwarf/semidwarf genes have been identified in different melon varieties,but none of them have been cloned,and little is known about the molecular mechanisms underlying internode elongation in melon.Here,we report map-based cloning and functional characterization of the first semidwarf gene short internode(Cmsi)in melon,which encodes an ERECTA-like receptor kinase regulating internode elongation.Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of the main stem during internode elongation.The expression level of CmSI was positively correlated with stem length in the different melon varieties examined.Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator of internode elongation in both species.Phytohormone quantitation and transcriptome analysis showed that the auxin content and the expression levels of a number of genes involved in the auxin signaling pathway were altered in the semidwarf mutant,including several well-known auxin transporters,such as members of the ABCB family and PINFORMED genes.A melon polar auxin transport protein CmPIN2 was identified by protein–protein interaction assay as physically interacting with CmSI to modulate auxin signaling.Thus,CmSI functions in an auxin-dependent regulatory pathway to control internode elongation in melon.Our findings revealed that the ERECTA family gene CmSI regulates stem elongation in melon through auxin signaling,which can directly affect polar auxin transport.展开更多
Germplasm collections are a crucial resource to conserve natural genetic diversity and provide a source of novel traits essential for sustained crop improvement.Optimal collection,preservation and utilization of these...Germplasm collections are a crucial resource to conserve natural genetic diversity and provide a source of novel traits essential for sustained crop improvement.Optimal collection,preservation and utilization of these materials depends upon knowledge of the genetic variation present within the collection.Here we use the high-throughput genotyping-by-sequencing(GBS)technology to characterize the United States National Plant Germplasm System(NPGS)collection of cucumber(Cucumis sativus L.).The GBS data,derived from 1234 cucumber accessions,provided more than 23 K high-quality single-nucleotide polymorphisms(SNPs)that are well distributed at high density in the genome(~1 SNP/10.6 kb).The SNP markers were used to characterize genetic diversity,population structure,phylogenetic relationships,linkage disequilibrium,and population differentiation of the NPGS cucumber collection.These results,providing detailed genetic analysis of the U.S.cucumber collection,complement NPGS descriptive information regarding geographic origin and phenotypic characterization.We also identified genome regions significantly associated with 13 horticulturally important traits through genome-wide association studies(GWAS).Finally,we developed a molecularly informed,publicly accessible core collection of 395 accessions that represents at least 96%of the genetic variation present in the NPGS.Collectively,the information obtained from the GBS data enabled deep insight into the diversity present and genetic relationships among accessions within the collection,and will provide a valuable resource for genetic analyses,gene discovery,crop improvement,and germplasm preservation.展开更多
Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sati...Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.展开更多
Cucumber,Cucumis sativus L.(2n=2x=14),is an important vegetable crop worldwide.It was the first specialty crop with a publicly available draft genome.Its relatively small,diploid genome,short life cycle,and selfcompat...Cucumber,Cucumis sativus L.(2n=2x=14),is an important vegetable crop worldwide.It was the first specialty crop with a publicly available draft genome.Its relatively small,diploid genome,short life cycle,and selfcompatible mating system offers advantages for genetic studies.In recent years,significant progress has been made in molecular mapping,and identification of genes and QTL responsible for key phenotypic traits,but a systematic review of the work is lacking.Here,we conducted an extensive literature review on mutants,genes and QTL that have been molecularly mapped or characterized in cucumber.We documented 81 simply inherited trait genes or major-effect QTL that have been cloned or fine mapped.For each gene,detailed information was compiled including chromosome locations,allelic variants and associated polymorphisms,predicted functions,and diagnostic markers that could be used for marker-assisted selection in cucumber breeding.We also documented 322 QTL for 42 quantitative traits,including 109 for disease resistances against seven pathogens.By alignment of these QTL on the latest version of cucumber draft genomes,consensus QTL across multiple studies were inferred,which provided insights into heritable correlations among different traits.Through collaborative efforts among public and private cucumber researchers,we identified 130 quantitative traits and developed a set of recommendations for QTL nomenclature in cucumber.This is the first attempt to systematically summarize,analyze and inventory cucumber mutants,cloned or mapped genes and QTL,which should be a useful resource for the cucurbit research community.展开更多
The gene RB is derived from the wild potato species S. bulbocastanum and confers partial resistance to late blight, caused by the oomycete pathogen Phytophthora infestans. In order to investigate whether a single stra...The gene RB is derived from the wild potato species S. bulbocastanum and confers partial resistance to late blight, caused by the oomycete pathogen Phytophthora infestans. In order to investigate whether a single strain of P. infestans can adapt to overcome this partial resistance source, we subjected RB containing leaflets to multiple rounds of infection with P. infestans, with a culture isolated from a lesion used to infect the next leaflet (a passage). A parallel line of passages was done using susceptible leaflets as hosts. At the end of the experiment, P. infestans strains passaged through resistant or susceptible leaflets were compared for infection efficiency and lesion size. Variants of the P. infestans effector family IPI-O, some of which are recognized by the RB protein to elicit resistance, were cloned and sequenced to determine whether variation occurred during selection on the partially resistant host. Our results show that after 20 rounds of selection, no breakdown in RB resistance took place. In fact, the strain that was continually passaged through the partially resistant host produced smaller lesions on susceptible leaflets and had a lower infection frequency than the strain passaged through susceptible cultivar Katahdin. No changes within IPI-O coding regions were detected after selection on the hosts with RB. Our results indicate that individual strains of P. infestans are not capable of rapidly overcoming RB resistance even when it is the only host available.展开更多
Cucumber,Cucumis sativus is an important vegetable crop,and gynoecy has played a critical role in yield increase of hybrid cucumber production.Cucumber has a unique genetic system for gynoecious sex expression,which i...Cucumber,Cucumis sativus is an important vegetable crop,and gynoecy has played a critical role in yield increase of hybrid cucumber production.Cucumber has a unique genetic system for gynoecious sex expression,which is determined by the copy number variation(CNV)-based,dominant,and dosage-dependent femaleness(F)locus.However,this gynoecy expression system seems unstable since monecious plants could often be found in Fdependent gynoecious cucumber inbreds.We hypothesized that gynoecy instability(gynoecy loss)may be due to unequal crossing over(UCO)during meiosis among repeat units of the CNV.In this study,using high throughput genome resequencing,fiber-FISH and genomic qPCR analyses,we first confirmed and refined the structure of the F locus,which was a CNV of a 30.2-kb tandem repeat.Gynoecious plants contained three genes:CsACS1,CsACS1G,and CsMYB,of which CsACS1G is a duplication of CsACS1 but with a recombinant distal promoter that may contribute to gynoecy sex expression.In two large populations from self-pollinated gynoecious inbred lines,‘gynoecy loss’mutants were identified with similar mutation rates(~0.12%).We show that these monecious mutants have lost CsACS1G.In addition,we identified gynoecious lines in natural populations that carry two copies of CSACS1G.We proposed a model to explain gynoecy instability in F-dependent cucumbers,which is caused by UCO among CSACS1/G units during meiosis.The findings present a convincing case that the phenotypic variation of an economically important trait is associated with the dynamic changes of copy numbers at the F locus.This work also has important implications in cucumber breeding.展开更多
The evaluation of plant-based feedstocks is an important aspect of biorefining.Nicotiana glauca is a solanaceous,non-food crop that produces large amounts of biomass and is well adapted to grow in suboptimal condition...The evaluation of plant-based feedstocks is an important aspect of biorefining.Nicotiana glauca is a solanaceous,non-food crop that produces large amounts of biomass and is well adapted to grow in suboptimal conditions.In the present article,compatible sequential solvent extractions were applied to N.glauca leaves to enable the generation of enriched extracts containing higher metabolite content comparing to direct leaf extracts.Typically,between 60 to 100 metabolite components were identified within the fractions.The occurrence of plant fatty acids,fatty acid alcohols,alkanes,sterols and terpenoids was detected by gas liquid chromatography-mass spectrometry(GC-MS)and metabolite identification was confirmed by comparison of physico-chemical properties displayed by available authentic standards.Collectively,co-products such waxes,oils,fermentable sugars,and terpenoids were all identified and quantified.The enriched fractions of N.glauca revealed a high level of readily extractable hydrocarbons,oils and high value co-products.In addition,the saccharification yield and cell wall composition analyses in the stems revealed the potential of the residue material as a promising lignocellulosic substrate for the production of fermentable sugars.In conclusion a multifractional cascade for valuable compounds/commodities has been development,that uses N.glauca biomass.These data have enabled the evaluation of N.glauca material as a potential feedstock for biorefining.展开更多
Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,i...Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,it is unknown if there is any integrating factor among them in the Plantae.We report that mutation of Csphy B or inactivation of Csphy B by shade inhibits lateral bud outgrowth in cucumber.Cucumber PHYTOCHROME INTERACTING FACTOR 4(Cs PIF4) interacts with Csphy B and directly binds to the promoter of CsBRC1 to activate CsBRC1 expression.CsBRC1 also directly promotes the expression of ABA biosynthesis gene 9-CIS-EPOXICAROTENOID DIOXIGENASE 3(CsNCED3).Functional disruption of Cs PIF4 decreased expression of CsBRC1 and CsNCED3,reduced ABA accumulation,and increased bud outgrowth in cucumber.Csnced3 mutants had reduced ABA levels and increased lateral bud outgrowth.These results suggest that a regulatory network involving Csphy B-Cs PIF4-CsBRC1 exists that integrates light signaling and ABA biosynthesis to modulate bud outgrowth.This provides a strategy to manipulate branch numbers in crop breeding to realize ideal branching characteristics to maximize yield.展开更多
Wild potato species have substantial phenotypic and physiological diversity. Here, we report a comprehen- sive assessment of wild and cultivated potato species based on genomic analyses of 201 accessions of Solanum se...Wild potato species have substantial phenotypic and physiological diversity. Here, we report a comprehen- sive assessment of wild and cultivated potato species based on genomic analyses of 201 accessions of Solanum section Petota. We sequenced the genomes of these 201 accessions and identified 6 487 006 high-quality single nucleotide polymorphisms （SNPs） from 167 accessions in clade 4 of Solanum section Petota, including 146 wild and 21 cultivated diploid potato accessions with a broad geographic distribution. Genome-wide genetic variation analysis showed that the diversity of wild potatoes is higher than that of cultivated potatoes, and much higher genetic diversity in the agronomically important disease resistance genes was observed in wild potatoes. Furthermore, by exploiting information about known quantitative trait loci （QTL）, we identified 609 genes under selection, including those correlated with the loss of bitterness in tubers and those involved in tuberization, two major domesticated traits of potato. Phylogenetic analyses revealed a north-south division of all species in clade 4, not just those in the S. brevicaule complex, and further supported So candolleanum as the progenitor of cultivated potato and the monophyletic origin of cultivated potato in southern Peru. In addition, we analyzed the genome of S. candolleanum and identified 529 genes lost in cultivated potato. Collectively, the molecular markers generated in this study provide a valuable resource for the identification of agronomicaUy important genes useful for potato breeding.展开更多
Tnt1 is an active retrotransposon originally identified in tobacco(Nicotiana tabacum L.)(Grandbastien et al.,1989),but its transposition activity could be activated through tissue culture in other plant species.The in...Tnt1 is an active retrotransposon originally identified in tobacco(Nicotiana tabacum L.)(Grandbastien et al.,1989),but its transposition activity could be activated through tissue culture in other plant species.The insertions are stable and inheritable in the progeny,which has made it a valuable and versatile tool for developing insertional mutagenesis libraries in several plant species.Here,we explored its utility for mutagenesis in cucumber(Cucumis sativus L.).T_3 Tnt1 transgenic cucumber plants were subjected to tissue culture to regenerate self-pollinated progeny.With PCR and analyses and Southern hybridization,we found regenerated plants maintained the original Tnt1 insertion and created new insertions suggesting characteristic re-transposition activity of Tnt1 during this process.Using genome walking,some flanking sequences of Tnt1 insertions were recovered in regenerated plants.The results demonstrated that Tnt1 could be stably inherited and re-transposable during tissue culture in cucumber and that it is feasible to use for developing an insertional mutagenesis library for cucumber.展开更多
基金This work was supported by the National Natural Science Foundation of China(31672159)the National Key Research and Development Program of China(2016YFD0101705)+1 种基金the Project of Beijing Agricultural Innovation Consortium(BAIC01-2017)to HZRthe Beijing Municipal Natural Science Foundation(6184043)to XWL.
文摘The cucumber(Cucumis sativus L.)is an important vegetable crop worldwide,and fruit trichomes or spines are an important trait for external fruit quality.The mechanisms underlying spine formation are not well understood,but the plant-specific NAC family of transcription factors may play important roles in fruit spine initiation and development.In this study,we conducted a genome-wide survey and identified 91 NAC gene homologs in the cucumber genome.Clustering analysis classified these genes into six subfamilies;each contained a varying number of NAC family members with a similar intron–exon structure and conserved motifs.Quantitative real-time PCR analysis revealed tissue-specific expression patterns of these genes,including 10 and 12 that exhibited preferential expression in the stem and fruit,respectively.Thirteen of the 91 NAC genes showed higher expression in the wild-type plant than in its near-isogenic trichome mutant,suggesting their important roles in fruit spine development.Exogenous application of four plant hormones promoted spine formation and increased spine density on the cucumber fruits;several NAC genes showed differential expression over time in response to phytohormone treatments on cucumber fruit,implying their essential roles in fruit-trichome development.Among the NAC genes identified,12 were found to be targets of 13 known cucumber micro-RNAs.Collectively,these findings provide a useful resource for further analysis of the interactions between NAC genes and genes underlying trichome organogenesis and development during fruit spine development in cucumber.
基金supported by funding from the National Natural Science Foundation of China(No.31225025)the National Basic Research Program of China(973 Program) (No.2012CB113900)+3 种基金the National High-tech R&D Program (863 Program)(No.2012AA100101)the Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences(CAAS-ASTIP-AGISCAAS)the leading talents of Guangdong province Program(No. 00201515)supported by the Shenzhen Municipal and Dapeng District governments
文摘Dwarfism is an important plant architecture trait in crop breeding（Peng et al.,1999;Sasaki el al.,2002）.In cucurbits.the compact plant type was proposed to develop new varieties for the once-over mechanical harvest for concentrated fruit set and higher densities（Li et al.,2011;Mondal et al.,2011）.
基金supported by the National Key Research and Development Program of China(2019YFD1000300)the National Natural Science Foundation of China(Nos.31672150 and 31872111).
文摘In plants,WUSCHEL-related homeobox1(WOX1)homologs promote lamina mediolateral outgrowth.However,the downstream components linking WOX1 and lamina development remain unclear.In this study,we revealed the roles of WOX1 in palmate leaf expansion in cucumber(Cucumis sativus).A cucumber mango fruit(mf)mutant,resulting from truncation of a WOX1-type protein(CsWOX1),displayed abnormal lamina growth and defects in the development of secondary and smaller veins.CsWOX1 was expressed in the middle mesophyll and leaf margins and rescued defects of the Arabidopsis wox1 prs double mutant.Transcriptomic analysis revealed that genes involved in auxin polar transport and auxin response were highly associated with leaf development.Analysis of the cucumber mf rl(round leaf)double mutant revealed that CsWOX1 functioned in vein development via PINOID(CsPID1)-controlled auxin transport.Overexpression of CsWOX1 in cucumber(CsWOX1-OE)affected vein patterning and produced‘butterfly-shaped’leaves.CsWOX1 physically interacted with CsTCP4a,which may account for the abnormal lamina development in the mf mutant line and the smaller leaves in the CsWOX1-OE plants.Our findings demonstrated that CsWOX1 regulates cucumber leaf vein development by modulating auxin polar transport;moreover,CsWOX1 regulates leaf size by controlling CIN-TCP genes.
基金supported by grants from the National Natural Science Foundation of China(31872133)the Project for Scientific and Technological Activities of Overseas Students of Henan Province,the Zhongyuan Youth Talent Support Program(ZYQR201912161)the Program for Science&Technology Innovation Talents in Universities of Henan Province(20HASTIT035).
文摘Plant height is one of the most important agronomic traits that directly determines plant architecture,and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lodging resistance and economic yield.At least four dwarf/semidwarf genes have been identified in different melon varieties,but none of them have been cloned,and little is known about the molecular mechanisms underlying internode elongation in melon.Here,we report map-based cloning and functional characterization of the first semidwarf gene short internode(Cmsi)in melon,which encodes an ERECTA-like receptor kinase regulating internode elongation.Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of the main stem during internode elongation.The expression level of CmSI was positively correlated with stem length in the different melon varieties examined.Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator of internode elongation in both species.Phytohormone quantitation and transcriptome analysis showed that the auxin content and the expression levels of a number of genes involved in the auxin signaling pathway were altered in the semidwarf mutant,including several well-known auxin transporters,such as members of the ABCB family and PINFORMED genes.A melon polar auxin transport protein CmPIN2 was identified by protein–protein interaction assay as physically interacting with CmSI to modulate auxin signaling.Thus,CmSI functions in an auxin-dependent regulatory pathway to control internode elongation in melon.Our findings revealed that the ERECTA family gene CmSI regulates stem elongation in melon through auxin signaling,which can directly affect polar auxin transport.
基金This research was supported by grants from USDA National Institute of Food and Agriculture Specialty Crop Research Initiative(2015-51181-24285).
文摘Germplasm collections are a crucial resource to conserve natural genetic diversity and provide a source of novel traits essential for sustained crop improvement.Optimal collection,preservation and utilization of these materials depends upon knowledge of the genetic variation present within the collection.Here we use the high-throughput genotyping-by-sequencing(GBS)technology to characterize the United States National Plant Germplasm System(NPGS)collection of cucumber(Cucumis sativus L.).The GBS data,derived from 1234 cucumber accessions,provided more than 23 K high-quality single-nucleotide polymorphisms(SNPs)that are well distributed at high density in the genome(~1 SNP/10.6 kb).The SNP markers were used to characterize genetic diversity,population structure,phylogenetic relationships,linkage disequilibrium,and population differentiation of the NPGS cucumber collection.These results,providing detailed genetic analysis of the U.S.cucumber collection,complement NPGS descriptive information regarding geographic origin and phenotypic characterization.We also identified genome regions significantly associated with 13 horticulturally important traits through genome-wide association studies(GWAS).Finally,we developed a molecularly informed,publicly accessible core collection of 395 accessions that represents at least 96%of the genetic variation present in the NPGS.Collectively,the information obtained from the GBS data enabled deep insight into the diversity present and genetic relationships among accessions within the collection,and will provide a valuable resource for genetic analyses,gene discovery,crop improvement,and germplasm preservation.
基金supported by Agriculture and Food Research Initiative Competitive Grant 2013-67013-21105 from the U.S. Department of Agriculture National Institute of Food to YWthe National Natural Science Foundation of China to YH (No. 31271350)
文摘Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.
基金supported by grants from the National Institute of Food and Agriculture,U.S.Department of Agriculture,under award numbers and 2015-51181-24285 and 2017-67013-26195(to Y.Q.W.)。
文摘Cucumber,Cucumis sativus L.(2n=2x=14),is an important vegetable crop worldwide.It was the first specialty crop with a publicly available draft genome.Its relatively small,diploid genome,short life cycle,and selfcompatible mating system offers advantages for genetic studies.In recent years,significant progress has been made in molecular mapping,and identification of genes and QTL responsible for key phenotypic traits,but a systematic review of the work is lacking.Here,we conducted an extensive literature review on mutants,genes and QTL that have been molecularly mapped or characterized in cucumber.We documented 81 simply inherited trait genes or major-effect QTL that have been cloned or fine mapped.For each gene,detailed information was compiled including chromosome locations,allelic variants and associated polymorphisms,predicted functions,and diagnostic markers that could be used for marker-assisted selection in cucumber breeding.We also documented 322 QTL for 42 quantitative traits,including 109 for disease resistances against seven pathogens.By alignment of these QTL on the latest version of cucumber draft genomes,consensus QTL across multiple studies were inferred,which provided insights into heritable correlations among different traits.Through collaborative efforts among public and private cucumber researchers,we identified 130 quantitative traits and developed a set of recommendations for QTL nomenclature in cucumber.This is the first attempt to systematically summarize,analyze and inventory cucumber mutants,cloned or mapped genes and QTL,which should be a useful resource for the cucurbit research community.
文摘The gene RB is derived from the wild potato species S. bulbocastanum and confers partial resistance to late blight, caused by the oomycete pathogen Phytophthora infestans. In order to investigate whether a single strain of P. infestans can adapt to overcome this partial resistance source, we subjected RB containing leaflets to multiple rounds of infection with P. infestans, with a culture isolated from a lesion used to infect the next leaflet (a passage). A parallel line of passages was done using susceptible leaflets as hosts. At the end of the experiment, P. infestans strains passaged through resistant or susceptible leaflets were compared for infection efficiency and lesion size. Variants of the P. infestans effector family IPI-O, some of which are recognized by the RB protein to elicit resistance, were cloned and sequenced to determine whether variation occurred during selection on the partially resistant host. Our results show that after 20 rounds of selection, no breakdown in RB resistance took place. In fact, the strain that was continually passaged through the partially resistant host produced smaller lesions on susceptible leaflets and had a lower infection frequency than the strain passaged through susceptible cultivar Katahdin. No changes within IPI-O coding regions were detected after selection on the hosts with RB. Our results indicate that individual strains of P. infestans are not capable of rapidly overcoming RB resistance even when it is the only host available.
基金supported by the National Natural Science Foundation of China(Nos.31672150 and 31872111)the Fundamental Research Fund for the Central Universities(2452016004)and the Key Research and Development Plan(2018NY-034)of Shaanxi Province.Work in Y.Q.W.’s lab was supported by USDA National Institute of Food and Agriculture under following award numbers 2015-51181-24285 and 2017-67013-26195.USDA is an equal opportunity provider and employer.
文摘Cucumber,Cucumis sativus is an important vegetable crop,and gynoecy has played a critical role in yield increase of hybrid cucumber production.Cucumber has a unique genetic system for gynoecious sex expression,which is determined by the copy number variation(CNV)-based,dominant,and dosage-dependent femaleness(F)locus.However,this gynoecy expression system seems unstable since monecious plants could often be found in Fdependent gynoecious cucumber inbreds.We hypothesized that gynoecy instability(gynoecy loss)may be due to unequal crossing over(UCO)during meiosis among repeat units of the CNV.In this study,using high throughput genome resequencing,fiber-FISH and genomic qPCR analyses,we first confirmed and refined the structure of the F locus,which was a CNV of a 30.2-kb tandem repeat.Gynoecious plants contained three genes:CsACS1,CsACS1G,and CsMYB,of which CsACS1G is a duplication of CsACS1 but with a recombinant distal promoter that may contribute to gynoecy sex expression.In two large populations from self-pollinated gynoecious inbred lines,‘gynoecy loss’mutants were identified with similar mutation rates(~0.12%).We show that these monecious mutants have lost CsACS1G.In addition,we identified gynoecious lines in natural populations that carry two copies of CSACS1G.We proposed a model to explain gynoecy instability in F-dependent cucumbers,which is caused by UCO among CSACS1/G units during meiosis.The findings present a convincing case that the phenotypic variation of an economically important trait is associated with the dynamic changes of copy numbers at the F locus.This work also has important implications in cucumber breeding.
基金Open Access funding enabled and organized by Projekt DEALThe research from the MultiBioPro project leading to these results has received funding from the European Union’s Seventh Framework Programme for research,technological development and demonstration under grant agreement 311804Further funding from the BBSRC 21EBTA-Celfacto project is acknowledged by PDF.
文摘The evaluation of plant-based feedstocks is an important aspect of biorefining.Nicotiana glauca is a solanaceous,non-food crop that produces large amounts of biomass and is well adapted to grow in suboptimal conditions.In the present article,compatible sequential solvent extractions were applied to N.glauca leaves to enable the generation of enriched extracts containing higher metabolite content comparing to direct leaf extracts.Typically,between 60 to 100 metabolite components were identified within the fractions.The occurrence of plant fatty acids,fatty acid alcohols,alkanes,sterols and terpenoids was detected by gas liquid chromatography-mass spectrometry(GC-MS)and metabolite identification was confirmed by comparison of physico-chemical properties displayed by available authentic standards.Collectively,co-products such waxes,oils,fermentable sugars,and terpenoids were all identified and quantified.The enriched fractions of N.glauca revealed a high level of readily extractable hydrocarbons,oils and high value co-products.In addition,the saccharification yield and cell wall composition analyses in the stems revealed the potential of the residue material as a promising lignocellulosic substrate for the production of fermentable sugars.In conclusion a multifractional cascade for valuable compounds/commodities has been development,that uses N.glauca biomass.These data have enabled the evaluation of N.glauca material as a potential feedstock for biorefining.
基金supported by grants from the National Natural Science Foundation of China(32372699, 32025033, and 32102387)Key R&D Program of Shandong Province,China (2024LZGCQY006)S&T Program of Hebei (22326308D)。
文摘Shoot branching is an important crop agronomic trait that directly affects plant architecture and crop productivity.Although phytochrome B(phy B),BRANCHED1(BRC1),and abscisic acid(ABA) mediate axillary bud outgrowth,it is unknown if there is any integrating factor among them in the Plantae.We report that mutation of Csphy B or inactivation of Csphy B by shade inhibits lateral bud outgrowth in cucumber.Cucumber PHYTOCHROME INTERACTING FACTOR 4(Cs PIF4) interacts with Csphy B and directly binds to the promoter of CsBRC1 to activate CsBRC1 expression.CsBRC1 also directly promotes the expression of ABA biosynthesis gene 9-CIS-EPOXICAROTENOID DIOXIGENASE 3(CsNCED3).Functional disruption of Cs PIF4 decreased expression of CsBRC1 and CsNCED3,reduced ABA accumulation,and increased bud outgrowth in cucumber.Csnced3 mutants had reduced ABA levels and increased lateral bud outgrowth.These results suggest that a regulatory network involving Csphy B-Cs PIF4-CsBRC1 exists that integrates light signaling and ABA biosynthesis to modulate bud outgrowth.This provides a strategy to manipulate branch numbers in crop breeding to realize ideal branching characteristics to maximize yield.
文摘Wild potato species have substantial phenotypic and physiological diversity. Here, we report a comprehen- sive assessment of wild and cultivated potato species based on genomic analyses of 201 accessions of Solanum section Petota. We sequenced the genomes of these 201 accessions and identified 6 487 006 high-quality single nucleotide polymorphisms （SNPs） from 167 accessions in clade 4 of Solanum section Petota, including 146 wild and 21 cultivated diploid potato accessions with a broad geographic distribution. Genome-wide genetic variation analysis showed that the diversity of wild potatoes is higher than that of cultivated potatoes, and much higher genetic diversity in the agronomically important disease resistance genes was observed in wild potatoes. Furthermore, by exploiting information about known quantitative trait loci （QTL）, we identified 609 genes under selection, including those correlated with the loss of bitterness in tubers and those involved in tuberization, two major domesticated traits of potato. Phylogenetic analyses revealed a north-south division of all species in clade 4, not just those in the S. brevicaule complex, and further supported So candolleanum as the progenitor of cultivated potato and the monophyletic origin of cultivated potato in southern Peru. In addition, we analyzed the genome of S. candolleanum and identified 529 genes lost in cultivated potato. Collectively, the molecular markers generated in this study provide a valuable resource for the identification of agronomicaUy important genes useful for potato breeding.
基金supported by the National Natural Science Foundation of China(No.31471156)the Agri-X Project of Shanghai Jiao Tong University(Agri-X2015002)the Shanghai Graduate Education and Innovation Program(Horticulture)
文摘Tnt1 is an active retrotransposon originally identified in tobacco(Nicotiana tabacum L.)(Grandbastien et al.,1989),but its transposition activity could be activated through tissue culture in other plant species.The insertions are stable and inheritable in the progeny,which has made it a valuable and versatile tool for developing insertional mutagenesis libraries in several plant species.Here,we explored its utility for mutagenesis in cucumber(Cucumis sativus L.).T_3 Tnt1 transgenic cucumber plants were subjected to tissue culture to regenerate self-pollinated progeny.With PCR and analyses and Southern hybridization,we found regenerated plants maintained the original Tnt1 insertion and created new insertions suggesting characteristic re-transposition activity of Tnt1 during this process.Using genome walking,some flanking sequences of Tnt1 insertions were recovered in regenerated plants.The results demonstrated that Tnt1 could be stably inherited and re-transposable during tissue culture in cucumber and that it is feasible to use for developing an insertional mutagenesis library for cucumber.
