Microsatellites or SSRs as powerful genetic markers have widely been used in genetics and evolutionary biology in common wheat. Because of the high polymorphism, newly synthesized hexaploid wheat has been used in the ...Microsatellites or SSRs as powerful genetic markers have widely been used in genetics and evolutionary biology in common wheat. Because of the high polymorphism, newly synthesized hexaploid wheat has been used in the construction of genetic segregation population for SSR markers, However, data on the evolution of microsatellites during the polyploidization event of hexaploid wheat are limited. In this study, 66 pairs of specific to A/B genome SSR patterns among newly synthesized hexaploid wheat, the donor tetraploid wheat and Aegilops tauschii were compared. The results indicated that most SSR markers were conserved during the polyploidization events of newly synthetic hexaploid wheat, from Triticum turgidum and Ae. tauschii. Over 70% A/B genome specific SSR markers could amplify the SSR sequences from the D genome ofAe. tauschii. Most amplified fragments from Ae, tauschii were detected in synthetic hexaploid at corresponding positions with the same sizes and patterns as in its parental Ae. tauschii. This suggested that these SSR markers, specific for A/B genome in common wheat, could amplify SSR products of D genome besides A/B genome in the newly synthesized hexaploid wheat, that is, these SSR primers specific for A/B genome in common wheat were nonspecific for the A/B genome in the synthetic hexaploid wheat. In addition, one amplified Ae. tauschii product was not detected in the newly synthetic hexaploid wheat. An extra-amplified product was found in the newly synthetic hexaploid wheat. These results suggested that caution should be taken when using SSR marker to genotype newly synthetic hexaploid wheat.展开更多
Synthetic hexaploid wheat （Triticum turgidum x Aegilops tauschii） was created to explore for novel genes from T. turgidum and Ae. tauschii that can be used for common wheat improvement. In the present paper, researc...Synthetic hexaploid wheat （Triticum turgidum x Aegilops tauschii） was created to explore for novel genes from T. turgidum and Ae. tauschii that can be used for common wheat improvement. In the present paper, research advances on the utilization of synthetic hexaploid wheat for wheat genetic improvement in China are reviewed. Over 200 synthetic hexaploid wheat （SHW） accessions from the International Maize and Wheat Improvement Centre （CIMMYT） were introduced into China since 1995. Four cultivars derived from these, Chuanmai 38, Chuanmai 42, Chuanmai 43 and Chuanmai 47, have been released in China. Of these, Chuanmai 42, with large kernels and resistance to stripe rust, had the highest average yield （〉 6 t/ha） among all cultivars over two years in Sichuan provincial yield trials, outyielding the commercial check cultivar Chuanmai 107 by 22,7%. Meanwhile, by either artificial chromosome doubling via colchicine treatment or spontaneous chromosome doubling via a union of unreduced gametes （2n） from T. turgidum-Ae, tauschii hybrids, new SHW lines were produced in China. Mitotic-like meiosis might be the cytological mechanism of spontaneous chromosome doubling. SHW lines with genes for spontaneous chromosome doubling may be useful for producing new SHW-alien amphidiploids and double haploid in wheat genetic improvement.展开更多
To determine the effect of 6 ＋ 8 and 1.5 ＋ 10 HMW-GS of synthetic hexaploid wheat （SHW） on main quality parameters of wheat, a set of recombinant inbred lines （RILs） derived from the cross between a SHW with N,...To determine the effect of 6 ＋ 8 and 1.5 ＋ 10 HMW-GS of synthetic hexaploid wheat （SHW） on main quality parameters of wheat, a set of recombinant inbred lines （RILs） derived from the cross between a SHW with N, 6 ＋ 8, 1.5 ＋ 10 HMW-GS and a cultivar Chuanyu 12-1 （CY 12-1） with 1, 7 ＋ 8, 2 ＋ 12 were planted in three environments in 2005 and 2006 and totally 16 quality parameters were tested for each line. Significant differences in all tested quality parameters but flour yield were observed between the two parents. The mean values of the RILs were intermediate to the parents for grain and protein parameters and some farinograph parameters, flour water absorption （FWA）, and farinograph softening （SOF） but beyond parents at dough stability time （DST）, breakdown time （BRT）, quality number （QN）, noodle score （NS）, and loaf volume （LOV）. All of the quality traits, especially in grain hardness （GH）, zeleny sedimentation volume （SED）, and most of farinograph parameters had significant difference between the different HMW-GS components. The effects of different alleles of HMW-GS at same locus （Glu-A1 or Glu-B1 or GIu-D1） on the different quality parameters were also different and affected by the other two loci. For most of parameters tested, 6 ＋ 8 was better than 7 ＋ 8 and there was no difference between 1.5 ＋ 10 and 2 ＋ 12. End-use quality was greatly influenced by components of HMW-GS. The components of 1, 6 ＋ 8, 1.5 ＋ 10 had the highest LOV and bread score （BS） values, whereas the components of 1, 7＋ 8 and 1.5 ＋ 10 had the highest NS values. Noodle score performed a positive linear relationship with falling number （FN） and its relationships to other quality parameters were affected by environments. Loaf volume had a significant negative relationship to SOF and positive associations with most of quality parameters. It could be concluded that HMW-GS 6＋ 8 from SHW had better overall quality characteristics than 7 ＋ 8, whereas the effects of 1.5 ＋ 10 on quality was different in respect to quality parameters and the HMW-GS components. Synthetic hexaploid wheat with subunits 6 ＋ 8 and 1.5 ＋ 10 had the potentials to improve the end-use quality of wheat cultivars.展开更多
Synthetic hexaploid wheat （SHW） represents a valuable source of new resistances to a range of biotic and abiotic stresses. A recombinant inbred line （RIL） population with 127 recombinant inbred lines derived from ...Synthetic hexaploid wheat （SHW） represents a valuable source of new resistances to a range of biotic and abiotic stresses. A recombinant inbred line （RIL） population with 127 recombinant inbred lines derived from a SHW-derived variety Chuanmai 42 crossing with a Chinese spring wheat variety Chuannong 16 was used to map QTLs for agronomic traits including grain yield, grains per square meter, thousand-kernel weight, spikes per square meter, grain number per spike, grains weight per spike, and biomass yield. The population was genotyped using 184 simple-sequence repeat （SSR） markers and 34 sequence-related amplified polymorphism （SRAP） markers. Of 76 QTLs （LOD〉2.5） identified, 42 were found to have a positive effect from Chuanmai 42. The QTL QGy.saas-4D.2 associated with grain yield on chromosome 4D was detected in four of the six environments and the combined analysis, and the mean yield, across six environments, of individuals carrying the Chuanmai 42 allele at this locus was 8.9% higher than that of those lines carrying the Chuannong 16 allele. Seven clusters of the yield-coincident QTLs were detected on 1A, 4A, 3B, 5B, 4D, and 7D.展开更多
Synthetic hexaploid wheat(SHW),possesses numerous genes for drought that can help breeding for drought-tolerant wheat varieties.We evaluated 10 root traits at seedling stage in 111 F9 recombinant inbred lines derived ...Synthetic hexaploid wheat(SHW),possesses numerous genes for drought that can help breeding for drought-tolerant wheat varieties.We evaluated 10 root traits at seedling stage in 111 F9 recombinant inbred lines derived from a F2 population of a SHW line(SHW-L1)and a common wheat line,under normal(NC)and polyethylene glycol-simulated drought stress conditions(DC).We mapped quantitative trait loci(QTLs)for root traits using an enriched high-density genetic map containing 120370 single nucleotide polymorphisms(SNPs),733 diversity arrays technology markers(DArT)and 119 simple sequence repeats(SSRs).With four replicates per treatment,we identified 19 QTLs for root traits under NC and DC,and 12 of them could be consistently detected with three or four replicates.Two novel QTLs for root fresh weight and root diameter under NC explained 9 and 15.7%of the phenotypic variation respectively,and six novel QTLs for root fresh weight,the ratio of root water loss,total root surface area,number of root tips,and number of root forks under DC explained 8.5–14%of the phenotypic variation.Here seven of eight novel QTLs could be consistently detected with more than three replicates.Results provide essential information for fine-mapping QTLs related to drought tolerance that will facilitate breeding drought-tolerant wheat cultivars.展开更多
Ninety-five synthetic hexaploid wheats （2n = 6x = 42, AABBDD） were analyzed using 45 microsatellite markers to investigate the potential genetic diversity in wheat breeding programs. A total of 326 alleles were dete...Ninety-five synthetic hexaploid wheats （2n = 6x = 42, AABBDD） were analyzed using 45 microsatellite markers to investigate the potential genetic diversity in wheat breeding programs. A total of 326 alleles were detected by these microsatellite primer pairs, with an average of 6.65 alleles per locus. The polymorphic information content （PIC）, Simpson index （SI）, and genetic similarity （GS） coefficient showed that the D genome is of the highest genetic diversity among the A, B, and D genomes in the synthetic hexaploid wheats. The results also indicated that the synthetic hexaploid wheat is an efficient way to enrich wheat genetic backgrounds, especially to use the genetic variations of the D genome from Aegilops squarrosa for wheat improvement. The UPGMA dendogram, based on a similarity matrix by a simple matching coeff＇lcient algorithm, delineated the above accessions into 5 major clusters and was in accordance with the available pedigree information. The results demonstrated the utility of microsatellite markers in detecting DNA polymorphism and estimating genetic diversity.展开更多
In order to widen gene germplasm for kernel hardness in triticale, 60 synthetic hexaploid triticales were tested by the single kernel characterization system(SKCS) and secaloindoline alleles were identified by sequenc...In order to widen gene germplasm for kernel hardness in triticale, 60 synthetic hexaploid triticales were tested by the single kernel characterization system(SKCS) and secaloindoline alleles were identified by sequencing. Phenot^ing showed that frequencies of soft, mixed and hard genotypes were 43.3%, 48.3%, and 8.4%, respectively. Genotyping identified three known secaloindoline-a alleles and four known secaloindoline-b alleles. Three new Sina-Rl alleles were designated Sina-Rld, Sina-Rle and Sina-Rlf. Compared to Sina-Dlc, Sina-Rld showed four point mutations causing changes in four amino acids, Sina-Rle had one point mutation causing an alanine to glycine substitution, and Sina-Rlf possessed five point mutations but produced the same amino add sequence as Sina-Rld. Two new Sinb-Rl alleles were discovered and designated Sinb-Rle and Sinb-Rl/. Compared to Sinb-Rla, Sinb-Rle possessed a triplet-code insertion and four point mutations causing a cysteine insertion and two amino acid substitutions, and Sinb-Rl/possessed three point mutations causing a cysteine insertion and a change of arginine to glycine.Association of hardness index with secaloindoline alleles indicated t±iat SKCS of the Sina-Rld genotype was significantly lower than that of Sina-Rle, and Sinb-Rle was significantly lower than that of the Sinb-Rld genotype. A total of eight allelic combinations of secaloindoline genes were identified; Sma-Rld/Sinb-Rle and Sina-Rle/Sinb-Rld were relatively prevalent in the triticales surveyed. The results provide valuable information for further use of these germplasms in triticale breeding program due to the diverse polymorphism in secaloindoline genes.展开更多
Yellow rust of wheat （caused by Puccinia striiformis Westend. f. sp. tritici Eriks.） has been periodically epidemic and severely damaged wheat production in China. The development of resistant cultivars could be an ...Yellow rust of wheat （caused by Puccinia striiformis Westend. f. sp. tritici Eriks.） has been periodically epidemic and severely damaged wheat production in China. The development of resistant cultivars could be an effective way to reduce yield losses of wheat caused by yellow rust. Rust reaction tests and genetic analysis indicated that M08, the synthetic hexaploid wheat derived from hybridization between Triticum durum （2n = 6X = 28; genome AABB） and Aegilops tauschii （2n = 2X = 14; genome DD）, showed resistance to current prevailing yellow rust races at seedling stage, which was controlled by a single dominant gene, designated as YrAm. Bulked segregant analysis was used to identify microsatellite markers linked to gene YrAm in an F2 population derived from cross M08 （resistant） × Jinan 17 （susceptible）. Three microsatellite marker loci Xgwm77, Xgwm285, and Xgwml31 located on chromosome 3B were mapped to the YrAm locus. Xgwml31 was the closest marker locus and showed a linkage distance of 7.8 cM to the resistance locus. Thus, it is assumed that YrAm for resistance to yellow rust may be derived from Triticum durum and is located on the long arm of chromosome 3B.展开更多
The F 1 and F 4 plants of 'synthetic hexaploid wheat/common wheat'crosses and part of their parents were inoculated with Fusarium graminearum to evaluate FHB resistance.The results showed tht the scab resist...The F 1 and F 4 plants of 'synthetic hexaploid wheat/common wheat'crosses and part of their parents were inoculated with Fusarium graminearum to evaluate FHB resistance.The results showed tht the scab resistance in the F 1 varied with the synthetic wheat accessions used as crossing parents.In the F 4,some resistant head lines were generated from the crosses,although their parents had different scab resistance levels.It indicated that synthetic hexaploid wheat are useful in wheat breeding for scab resistance.展开更多
A narrow genetic base has hindered improvement of Brassica juncea(A^(j)A^(j)B^(j)B^(j)).In this study,large-scale genomic components were introduced from diploid ancestor species into modern B.juncea using a digenomic...A narrow genetic base has hindered improvement of Brassica juncea(A^(j)A^(j)B^(j)B^(j)).In this study,large-scale genomic components were introduced from diploid ancestor species into modern B.juncea using a digenomic hexaploid strategy.The hexaploids A^(j)A^(j)A^(r)A^(r)B^(j)B^(j) and A^(j)A^(j)B^(j)B^(j)B^(n)B^(n) were first developed from B.juncea×B.rapa(A^(r)A^(r))and B.juncea×B.nigra(B^(n)B^(n)),and then crossed with dozens of B.nigra and B.rapa,respectively.Both types of hexaploid showed high pollen fertility and moderate seed set throughout the S_(1) to S_(3) generations,and could be crossed with diploid progenitor species under field conditions,in particular for the combination of A^(j)A^(j)B^(j)B^(j)B^(n)B^(n)×B.rapa.Thirty A^(j)A^(r)B^(n)B^(j)-type and 31 A^(j)A^(r)B^(n)B^(j)-type B.juncea resources were generated,of which the A^(j)A^(r)B^(n)B^(j) type showed higher fertility.Of these new-type B.juncea resources,97 individual plants were genotyped with 42 simple sequence repeat markers,together with 16 current B.juncea accessions and 30 hexaploid plants.Based on 180 polymorphic loci,the new-type B.juncea resources and current B.juncea were separated clearly into distinct groups,with large genetic distance between the new-type B.juncea resources and current B.juncea.Our study provides a novel approach to introducing large-scale genomic components from diploid ancestor species into B.juncea.展开更多
This study evaluated the quality potential of seven synthetic hexaploid wheats(2 n=6 x=42, AABBDD) expressing only allelic variation at Glu-D1 of Aegilops tauschii(SHWSD). Major quality parameters related to dough str...This study evaluated the quality potential of seven synthetic hexaploid wheats(2 n=6 x=42, AABBDD) expressing only allelic variation at Glu-D1 of Aegilops tauschii(SHWSD). Major quality parameters related to dough strength, gluten proteins(including high-molecular-weight glutenin subunits(HMW-GS) and low-molecular-weight glutenin subunits(LMW-GS), gliadins), and their ratios between SHWSD and the weak gluten wheat control Chuannong 16(CN16) were measured in at least three environments(except STD7). The zeleny sedimentation value(ZSV), dough development time(DDT), dough stability time(DST), and farinograph quality number(FQN) of SHWSD were considered stable under different environments, with their respective ranges being 8.00–17.67 mL, 0.57–1.50 min, 0.73–1.80 min, and 9.50–27.00. The ZSV, DDT, DST, and FQN of SHWSD were smaller than those of CN16, suggesting that SHWSD had a weaker dough strength than CN16. Although SHWSD had a lower gluten index than CN16, its wet and dry gluten contents were similar to or even higher than those of CN16 in all environments tested. The protein content of grains(12.81–18.21%) and flours(14.20–20.31%) in SHWSD was higher than that in CN16. The amount of HMW-GS in SHWSD sharply decreased under the expression of fewer HMW-GS genes, and the LMW-GS, gliadins, and total glutenins were simultaneously increased in SHWSD in comparison with CN16. Moreover, SHWSD had higher ratios of LMWGS/glutenin and gliadin/glutenin but a lower ratio of HMW-GS/glutenin than CN16. These results provide necessary information for the utilization of SHWSD in weak-gluten wheat breeding.展开更多
The core collection of red-seeded winter hexaploid triticale with different pre-harvest sprouting (PHS) resistance has been evaluated for the allelic structure of the gene VIVIPAROUS-1B (Vp-1B) with STS molecular mark...The core collection of red-seeded winter hexaploid triticale with different pre-harvest sprouting (PHS) resistance has been evaluated for the allelic structure of the gene VIVIPAROUS-1B (Vp-1B) with STS molecular marker. The discovered structure of the collection was as follows: 50.0% and 41.7% of the collection carries Vp-1Bа and Vp-1Bc alleles, respectively, while 8,3% possesses both of them. As a result of the seed color estimation, the collection has been divided into two groups: with dark red seeds and light red seeds. The allele Vp-1Bc has appeared to be associated with PHS resistance while Vp-1Ba with PHS susceptibility in the triticale accessions with light red seeds only. The influence of the seed color and allelic state of Vp-1B on PHS resistance in triticale is discussed.展开更多
In order to study the roles of members of HKT gene fanfily in wheat, TaHKT2 ; 2 was isolated by using homologous cloning strategy and screening genomic BAC library. TaHKT2; 2 genes were mapped on chromosomes 7A, 7B an...In order to study the roles of members of HKT gene fanfily in wheat, TaHKT2 ; 2 was isolated by using homologous cloning strategy and screening genomic BAC library. TaHKT2; 2 genes were mapped on chromosomes 7A, 7B and 7D, named as TaHKT2; 2-7A, TaHKT2; 2-7B, and TaHKT2; 2-7D, respectively. TaHKT2 ; 2 and TaHKT2 ; 1 had the same genetic structure, composed of three exons and two introns, and formed a cluster with TaHKT2 ; 1 on the phylogenetic tree of plant HKT transporters. The coding sequences of TaHKT2 ; 2-7A, TaHKT2 ; 2-7B, and TaHKT2 ; 2-7D were 1 602, 1 602 and 1 596 bp long, respectively, but TaHKT2 ;2-7D cDNA sequence was not isolated by RT-PCR in eight wheat varieties. The natural diversity of TaHKT2 ;2 genes was analyzed by cloning and sequencing from 12 wheat varieties. The results showed that TaHKT2;2-7A was found to be more diverse than TaHKT2; 2-7B and TaHKT2; 2-7D. Only a few bases changed in the alleles of TaHKT2 ; 2 genes in wheat. No amino-acid natural variation lay in the P-loops of deduced protein sequences of all alleles of TaHKT2 ; 2 in 12 wheat varieties. The identity of coding sequences was nmch higher than that of 5＇ flanking regions of TaHKT2 ; 2 genes. TaHKT2 ; 2 nfight be selected over the comse of wheat domestication and belonged to domestication gene.展开更多
The wild cotton diploid species (2n = 2x = 26) are important sources of useful traits such as high fiber quality, resistance to biotic and abiotic stresses etc., which can be introgressed into the cultivated tetraploi...The wild cotton diploid species (2n = 2x = 26) are important sources of useful traits such as high fiber quality, resistance to biotic and abiotic stresses etc., which can be introgressed into the cultivated tetraploid cotton <i>Gossypium hirsutum</i> L (2n = 4x = 52), for its genetic improvement. The African wild diploid species <i>G. longicalyx</i> Hutchinson and Lee could be used as donor of the desirable traits of fiber fineness and resistance to reniform nematode. However, hybridization of wild diploid species and cultivated tetraploid cotton encounters a sterility problem of the triploid (2n = 3x = 59), mainly due to ploidy. The restoration of the fertility can be done by creating an allohexaploid (2n = 6x = 78) through the doubling with colchicine of the sterile triploid chromosomes. With this method, a synthetic allohexaploid hybrid (<i>G. hirsutum</i> × <i>G. longicalyx</i>)2 has been obtained. This genotype was studied using phenotypic, cytological and molecular (AFLP) analyses in order to confirm its hybridity and its caryotype, and also to verify the expression of the desirable traits coming from <i>G. longicalyx</i>. The studied genotype showed a quite good level of pollen fertility (83%), and apart from larger seeds and some minor seedling anomalies, most of its morphological characteristics were intermediate between the two parental species. It had 78 chromosomes, proving its hexaploid status. Molecular analysis revealed 136 AFLP loci in this hexaploid, all from <i>G. hirsutum</i> and <i>G. longicalyx</i>, demonstrating its hybrid status. In addition, the hexaploid exhibited the useful traits of <i>G. longicalyx</i> with regard to its remarkable fiber fineness and its high resistance to the reniform nematode. This allohexaploid hybrid constitutes an interesting agronomic material, which can be used as a bridge for the transfer of useful agronomic traits from wild species to varieties of <i>G. hirsutum</i>.展开更多
With 17% of all crop area, wheat is the staple food for 40% of the world’s population. Improvement in bread wheat quality and yield in the context of sustainable agriculture is needed in the next decades to meet human
Jerusalem artichoke(Helianthus tuberosus)is a global multifunctional crop.It has wide applications in the food,health,feed,and biofuel industries and in ecological protection;it also serves as a germplasm pool for bre...Jerusalem artichoke(Helianthus tuberosus)is a global multifunctional crop.It has wide applications in the food,health,feed,and biofuel industries and in ecological protection;it also serves as a germplasm pool for breeding of the global oil crop common sunflower(Helianthus annuus).However,biological studies of Je-rusalem artichoke have been hindered by a lack of genome sequences,and its high polyploidy and large genome size have posed challenges to genome assembly.Here,we report a 21-Gb chromosome-level as-sembly of the hexaploid Jerusalem artichoke genome,which comprises 17 homologous groups,each with 6 pseudochromosomes.We found multiple large-scale chromosome rearrangements between Jerusalem artichoke and common sunflower,and our results show that the hexaploid genome of Jerusalem artichoke was formed by a hybridization event between a tetraploid and a diploid Helianthus species,followed by chromosome doubling of the hybrid,which occurred approximately 2 million years ago.Moreover,we iden-tied more copies of actively expressed genes involved in inulin metabolism and showed that these genes may still be undergoing loss of function or sub-or neofunctionalization.These genomic resources will pro-mote further biological studies,breeding improvement,and industrial utilization of Helianthus crops.展开更多
It was suggested that the rapid changes of DNA sequence and gene expression oc- curred at the early stages of allopolyploid formation. In this study, we revealed the microsatellite (SSR) differences between newly form...It was suggested that the rapid changes of DNA sequence and gene expression oc- curred at the early stages of allopolyploid formation. In this study, we revealed the microsatellite (SSR) differences between newly formed allopolyploids and their donor parents by using 21 primer sets specific for D genome of wheat. It was indicated that rapid changes had occurred in the “shock” process of the allopolyploid formation between tetraploid wheat and Aegilops tauschii. The changes of SSR flanking sequence resulted in appearance of novel bands or disappearance of parental bands. The disappearance of the parental bands showed much higher frequencies in comparison with that of appearance of novel bands. Disappearance of the parental bands was not random. The frequency of disappearance in tetraploid wheat was much higher than in Ae. tauschii, i. e. the disappearance frequency in AABB genome was much higher than in D genome. Changes of SSR flanking sequence occurred at the early stage of F1 hybrid or just after chro- mosome doubling. From the above results, it can be inferred that SSR flanking sequence region was very active and was amenable to change in the process of polyploidization. This suggested that SSR flanking sequence probably had special biological function at the early stage of ploy- ploidization. The rapid and directional changes at the early stage of polyploidization might con- tribute to the rapid evolution of the newly formed allopolyploid and allow the divergent genomes to act in harmony.展开更多
Three diploid （Triticum boeoticum, AA; Aegilops speltoides, BB and Ae. tauschii, DD）, two tetraplold （T. dlcoccoides, AABB and T. dicoccon, AABB） and one hexapioid （T. vulgare, AABBDD） varieties of wheat, which ...Three diploid （Triticum boeoticum, AA; Aegilops speltoides, BB and Ae. tauschii, DD）, two tetraplold （T. dlcoccoides, AABB and T. dicoccon, AABB） and one hexapioid （T. vulgare, AABBDD） varieties of wheat, which are very important In the evolution of wheat were chosen in this study. A pot experiment was carried out on the wheat under different water and nutrient conditions （i） to understand the differences in biomass, yield, water use efficiency （WUE）, and nutrient （N, P and K） use efficiency （uptake and utilization efficiency） among ploidies in the evolution of wheat; （li） to clarify the effect of water and nutrient conditions on water and nutrient use efficiency; and （ill） to assess the relationship of water and nutrient use efficiency in the evolution of wheat. Our results showed that from diploid to tetraplold then to hexaploid during the evolution of wheat, both root biomass and above-ground biomass Increased Initially and then decreased. Water consumption for transpiration decreased remarkably, correlating with the decline of the growth period, while grain yield, harvest index, WUE, N, P and K uptake efficiency, and N, P and K utilization efficiency Increased significantly. Grain yield, harvest index and WUE decreased In the same order： T. vulgare 〉 T. dicoccon 〉 T. dicoccoides 〉 Ae. tauschii 〉 Ae. speltoides 〉 T. boeoticum. Water stress significantly decreased root blomass, above-ground biomass, yield, and water consumption for transpiration by 47-52%, but remarkably Increased WUE. Increasing the nutrient supply increased wheat above-ground biomass, grain yield, harvest Index, water consumption for transpiration and WUE under different water levels, but reduced root blomass under drought conditions. Generally, water stress and low nutrient supply resulted in the lower nutrient uptake efficiency of wheat. However, water and nutrient application had no significant effects on nutrient utilization efficiency, suggesting that wheat nutrient utilization efficiency is mainly controlled by genotypes. Compared to the other two diploid wheats, Ae. squarrosa （DD） had significant higher WUE and nutrient utilization efficiency, Indicating that the D genome may carry genes controlling high efficient utilization of water and nutrient. Significant relation- ships were found between WUE and N, P and K utilization efficiency.展开更多
基金the project of Scientific Research Foundation for the Returned Overseas Chinese Scholars, New Century Excellent Talents in University (No. NCET-04-0908)Changjiang Scholars and Innovative Research Team in University (No. IRT0 453) of the Chinese Ministry of EducationNational Natural Science Foundation of China (No. 30270804), Education Department and Science and Technology Department of Sichuan Province.
文摘Microsatellites or SSRs as powerful genetic markers have widely been used in genetics and evolutionary biology in common wheat. Because of the high polymorphism, newly synthesized hexaploid wheat has been used in the construction of genetic segregation population for SSR markers, However, data on the evolution of microsatellites during the polyploidization event of hexaploid wheat are limited. In this study, 66 pairs of specific to A/B genome SSR patterns among newly synthesized hexaploid wheat, the donor tetraploid wheat and Aegilops tauschii were compared. The results indicated that most SSR markers were conserved during the polyploidization events of newly synthetic hexaploid wheat, from Triticum turgidum and Ae. tauschii. Over 70% A/B genome specific SSR markers could amplify the SSR sequences from the D genome ofAe. tauschii. Most amplified fragments from Ae, tauschii were detected in synthetic hexaploid at corresponding positions with the same sizes and patterns as in its parental Ae. tauschii. This suggested that these SSR markers, specific for A/B genome in common wheat, could amplify SSR products of D genome besides A/B genome in the newly synthesized hexaploid wheat, that is, these SSR primers specific for A/B genome in common wheat were nonspecific for the A/B genome in the synthetic hexaploid wheat. In addition, one amplified Ae. tauschii product was not detected in the newly synthetic hexaploid wheat. An extra-amplified product was found in the newly synthetic hexaploid wheat. These results suggested that caution should be taken when using SSR marker to genotype newly synthetic hexaploid wheat.
基金supported by the National 863 pro-gram (No. 2006AA10Z1C6)the National Natural Science Foundation of China (No. 30771338 and 30700495)+1 种基金"100-Talent Program" of Chinese Academy of Sciencesthe Science and Technology Department of Sichuan Province
文摘Synthetic hexaploid wheat （Triticum turgidum x Aegilops tauschii） was created to explore for novel genes from T. turgidum and Ae. tauschii that can be used for common wheat improvement. In the present paper, research advances on the utilization of synthetic hexaploid wheat for wheat genetic improvement in China are reviewed. Over 200 synthetic hexaploid wheat （SHW） accessions from the International Maize and Wheat Improvement Centre （CIMMYT） were introduced into China since 1995. Four cultivars derived from these, Chuanmai 38, Chuanmai 42, Chuanmai 43 and Chuanmai 47, have been released in China. Of these, Chuanmai 42, with large kernels and resistance to stripe rust, had the highest average yield （〉 6 t/ha） among all cultivars over two years in Sichuan provincial yield trials, outyielding the commercial check cultivar Chuanmai 107 by 22,7%. Meanwhile, by either artificial chromosome doubling via colchicine treatment or spontaneous chromosome doubling via a union of unreduced gametes （2n） from T. turgidum-Ae, tauschii hybrids, new SHW lines were produced in China. Mitotic-like meiosis might be the cytological mechanism of spontaneous chromosome doubling. SHW lines with genes for spontaneous chromosome doubling may be useful for producing new SHW-alien amphidiploids and double haploid in wheat genetic improvement.
基金the Sichuan Provincial Youth Foundation (04ZQ026-009)National 863 Pro-gram of China (2006AA10Z1C6)+1 种基金National Natural Science Foundation of China (30771338)Na-tional Key Technology R&D Program of China(2006BAD01A02, 2006BAD13B02)
文摘To determine the effect of 6 ＋ 8 and 1.5 ＋ 10 HMW-GS of synthetic hexaploid wheat （SHW） on main quality parameters of wheat, a set of recombinant inbred lines （RILs） derived from the cross between a SHW with N, 6 ＋ 8, 1.5 ＋ 10 HMW-GS and a cultivar Chuanyu 12-1 （CY 12-1） with 1, 7 ＋ 8, 2 ＋ 12 were planted in three environments in 2005 and 2006 and totally 16 quality parameters were tested for each line. Significant differences in all tested quality parameters but flour yield were observed between the two parents. The mean values of the RILs were intermediate to the parents for grain and protein parameters and some farinograph parameters, flour water absorption （FWA）, and farinograph softening （SOF） but beyond parents at dough stability time （DST）, breakdown time （BRT）, quality number （QN）, noodle score （NS）, and loaf volume （LOV）. All of the quality traits, especially in grain hardness （GH）, zeleny sedimentation volume （SED）, and most of farinograph parameters had significant difference between the different HMW-GS components. The effects of different alleles of HMW-GS at same locus （Glu-A1 or Glu-B1 or GIu-D1） on the different quality parameters were also different and affected by the other two loci. For most of parameters tested, 6 ＋ 8 was better than 7 ＋ 8 and there was no difference between 1.5 ＋ 10 and 2 ＋ 12. End-use quality was greatly influenced by components of HMW-GS. The components of 1, 6 ＋ 8, 1.5 ＋ 10 had the highest LOV and bread score （BS） values, whereas the components of 1, 7＋ 8 and 1.5 ＋ 10 had the highest NS values. Noodle score performed a positive linear relationship with falling number （FN） and its relationships to other quality parameters were affected by environments. Loaf volume had a significant negative relationship to SOF and positive associations with most of quality parameters. It could be concluded that HMW-GS 6＋ 8 from SHW had better overall quality characteristics than 7 ＋ 8, whereas the effects of 1.5 ＋ 10 on quality was different in respect to quality parameters and the HMW-GS components. Synthetic hexaploid wheat with subunits 6 ＋ 8 and 1.5 ＋ 10 had the potentials to improve the end-use quality of wheat cultivars.
基金supported by the Sichuan Provincial Youth Foundation,China (09ZQ026-086)the earmarked fund for Modern Agro-Industry Technology Research System,China (nycytx-03)+1 种基金the National 863 Program of China (2006AA10Z1C6)the National Natural Science Foundation of China (30771338 and30871532)
文摘Synthetic hexaploid wheat （SHW） represents a valuable source of new resistances to a range of biotic and abiotic stresses. A recombinant inbred line （RIL） population with 127 recombinant inbred lines derived from a SHW-derived variety Chuanmai 42 crossing with a Chinese spring wheat variety Chuannong 16 was used to map QTLs for agronomic traits including grain yield, grains per square meter, thousand-kernel weight, spikes per square meter, grain number per spike, grains weight per spike, and biomass yield. The population was genotyped using 184 simple-sequence repeat （SSR） markers and 34 sequence-related amplified polymorphism （SRAP） markers. Of 76 QTLs （LOD〉2.5） identified, 42 were found to have a positive effect from Chuanmai 42. The QTL QGy.saas-4D.2 associated with grain yield on chromosome 4D was detected in four of the six environments and the combined analysis, and the mean yield, across six environments, of individuals carrying the Chuanmai 42 allele at this locus was 8.9% higher than that of those lines carrying the Chuannong 16 allele. Seven clusters of the yield-coincident QTLs were detected on 1A, 4A, 3B, 5B, 4D, and 7D.
基金supported by the National Natural Science Foundation of China(31771794,91731305 and 31560388)the outstanding Youth Foundation of the Department of Science and Technology of Sichuan Province,China(2016JQ0040)+1 种基金the Key Technology Research and Development Program of the Department of Science and Technology of Sichuan Province,China(2016NZ0057)the International Science&Technology Cooperation Program of the Bureau of Science and Technology of Chengdu,China(2015DFA306002015-GH03-00008-HZ)。
文摘Synthetic hexaploid wheat(SHW),possesses numerous genes for drought that can help breeding for drought-tolerant wheat varieties.We evaluated 10 root traits at seedling stage in 111 F9 recombinant inbred lines derived from a F2 population of a SHW line(SHW-L1)and a common wheat line,under normal(NC)and polyethylene glycol-simulated drought stress conditions(DC).We mapped quantitative trait loci(QTLs)for root traits using an enriched high-density genetic map containing 120370 single nucleotide polymorphisms(SNPs),733 diversity arrays technology markers(DArT)and 119 simple sequence repeats(SSRs).With four replicates per treatment,we identified 19 QTLs for root traits under NC and DC,and 12 of them could be consistently detected with three or four replicates.Two novel QTLs for root fresh weight and root diameter under NC explained 9 and 15.7%of the phenotypic variation respectively,and six novel QTLs for root fresh weight,the ratio of root water loss,total root surface area,number of root tips,and number of root forks under DC explained 8.5–14%of the phenotypic variation.Here seven of eight novel QTLs could be consistently detected with more than three replicates.Results provide essential information for fine-mapping QTLs related to drought tolerance that will facilitate breeding drought-tolerant wheat cultivars.
文摘Ninety-five synthetic hexaploid wheats （2n = 6x = 42, AABBDD） were analyzed using 45 microsatellite markers to investigate the potential genetic diversity in wheat breeding programs. A total of 326 alleles were detected by these microsatellite primer pairs, with an average of 6.65 alleles per locus. The polymorphic information content （PIC）, Simpson index （SI）, and genetic similarity （GS） coefficient showed that the D genome is of the highest genetic diversity among the A, B, and D genomes in the synthetic hexaploid wheats. The results also indicated that the synthetic hexaploid wheat is an efficient way to enrich wheat genetic backgrounds, especially to use the genetic variations of the D genome from Aegilops squarrosa for wheat improvement. The UPGMA dendogram, based on a similarity matrix by a simple matching coeff＇lcient algorithm, delineated the above accessions into 5 major clusters and was in accordance with the available pedigree information. The results demonstrated the utility of microsatellite markers in detecting DNA polymorphism and estimating genetic diversity.
基金funded by the National Natural Science Foundation of China (31370031)National Key Research and Development Program of China (2016YFD0101802)+1 种基金Henan Major Science and Technology Projects (161100110500)Henan Science and Technology Innovation Outstanding Youth Foundation (174100510001)
文摘In order to widen gene germplasm for kernel hardness in triticale, 60 synthetic hexaploid triticales were tested by the single kernel characterization system(SKCS) and secaloindoline alleles were identified by sequencing. Phenot^ing showed that frequencies of soft, mixed and hard genotypes were 43.3%, 48.3%, and 8.4%, respectively. Genotyping identified three known secaloindoline-a alleles and four known secaloindoline-b alleles. Three new Sina-Rl alleles were designated Sina-Rld, Sina-Rle and Sina-Rlf. Compared to Sina-Dlc, Sina-Rld showed four point mutations causing changes in four amino acids, Sina-Rle had one point mutation causing an alanine to glycine substitution, and Sina-Rlf possessed five point mutations but produced the same amino add sequence as Sina-Rld. Two new Sinb-Rl alleles were discovered and designated Sinb-Rle and Sinb-Rl/. Compared to Sinb-Rla, Sinb-Rle possessed a triplet-code insertion and four point mutations causing a cysteine insertion and two amino acid substitutions, and Sinb-Rl/possessed three point mutations causing a cysteine insertion and a change of arginine to glycine.Association of hardness index with secaloindoline alleles indicated t±iat SKCS of the Sina-Rld genotype was significantly lower than that of Sina-Rle, and Sinb-Rle was significantly lower than that of the Sinb-Rld genotype. A total of eight allelic combinations of secaloindoline genes were identified; Sma-Rld/Sinb-Rle and Sina-Rle/Sinb-Rld were relatively prevalent in the triticales surveyed. The results provide valuable information for further use of these germplasms in triticale breeding program due to the diverse polymorphism in secaloindoline genes.
文摘Yellow rust of wheat （caused by Puccinia striiformis Westend. f. sp. tritici Eriks.） has been periodically epidemic and severely damaged wheat production in China. The development of resistant cultivars could be an effective way to reduce yield losses of wheat caused by yellow rust. Rust reaction tests and genetic analysis indicated that M08, the synthetic hexaploid wheat derived from hybridization between Triticum durum （2n = 6X = 28; genome AABB） and Aegilops tauschii （2n = 2X = 14; genome DD）, showed resistance to current prevailing yellow rust races at seedling stage, which was controlled by a single dominant gene, designated as YrAm. Bulked segregant analysis was used to identify microsatellite markers linked to gene YrAm in an F2 population derived from cross M08 （resistant） × Jinan 17 （susceptible）. Three microsatellite marker loci Xgwm77, Xgwm285, and Xgwml31 located on chromosome 3B were mapped to the YrAm locus. Xgwml31 was the closest marker locus and showed a linkage distance of 7.8 cM to the resistance locus. Thus, it is assumed that YrAm for resistance to yellow rust may be derived from Triticum durum and is located on the long arm of chromosome 3B.
文摘The F 1 and F 4 plants of 'synthetic hexaploid wheat/common wheat'crosses and part of their parents were inoculated with Fusarium graminearum to evaluate FHB resistance.The results showed tht the scab resistance in the F 1 varied with the synthetic wheat accessions used as crossing parents.In the F 4,some resistant head lines were generated from the crosses,although their parents had different scab resistance levels.It indicated that synthetic hexaploid wheat are useful in wheat breeding for scab resistance.
基金financially the National Key Research and Development Program of China(2018YFE0108000)the Natural Science Foundation of Chongqing(cstc2019jcyj-zdxm X0012)the Fundamental Research Funds for the Central Universities(XDJK2018B022,XDJK2018AA004)。
文摘A narrow genetic base has hindered improvement of Brassica juncea(A^(j)A^(j)B^(j)B^(j)).In this study,large-scale genomic components were introduced from diploid ancestor species into modern B.juncea using a digenomic hexaploid strategy.The hexaploids A^(j)A^(j)A^(r)A^(r)B^(j)B^(j) and A^(j)A^(j)B^(j)B^(j)B^(n)B^(n) were first developed from B.juncea×B.rapa(A^(r)A^(r))and B.juncea×B.nigra(B^(n)B^(n)),and then crossed with dozens of B.nigra and B.rapa,respectively.Both types of hexaploid showed high pollen fertility and moderate seed set throughout the S_(1) to S_(3) generations,and could be crossed with diploid progenitor species under field conditions,in particular for the combination of A^(j)A^(j)B^(j)B^(j)B^(n)B^(n)×B.rapa.Thirty A^(j)A^(r)B^(n)B^(j)-type and 31 A^(j)A^(r)B^(n)B^(j)-type B.juncea resources were generated,of which the A^(j)A^(r)B^(n)B^(j) type showed higher fertility.Of these new-type B.juncea resources,97 individual plants were genotyped with 42 simple sequence repeat markers,together with 16 current B.juncea accessions and 30 hexaploid plants.Based on 180 polymorphic loci,the new-type B.juncea resources and current B.juncea were separated clearly into distinct groups,with large genetic distance between the new-type B.juncea resources and current B.juncea.Our study provides a novel approach to introducing large-scale genomic components from diploid ancestor species into B.juncea.
基金the National Natural Science Foundation of China(31771783 and U1403185)the National Key R&D Program of China(2016YFD0100502 and 2017YFD0100903)the Sichuan Science and Technology Program,China(2018HH0113 and 2018HH0130)。
文摘This study evaluated the quality potential of seven synthetic hexaploid wheats(2 n=6 x=42, AABBDD) expressing only allelic variation at Glu-D1 of Aegilops tauschii(SHWSD). Major quality parameters related to dough strength, gluten proteins(including high-molecular-weight glutenin subunits(HMW-GS) and low-molecular-weight glutenin subunits(LMW-GS), gliadins), and their ratios between SHWSD and the weak gluten wheat control Chuannong 16(CN16) were measured in at least three environments(except STD7). The zeleny sedimentation value(ZSV), dough development time(DDT), dough stability time(DST), and farinograph quality number(FQN) of SHWSD were considered stable under different environments, with their respective ranges being 8.00–17.67 mL, 0.57–1.50 min, 0.73–1.80 min, and 9.50–27.00. The ZSV, DDT, DST, and FQN of SHWSD were smaller than those of CN16, suggesting that SHWSD had a weaker dough strength than CN16. Although SHWSD had a lower gluten index than CN16, its wet and dry gluten contents were similar to or even higher than those of CN16 in all environments tested. The protein content of grains(12.81–18.21%) and flours(14.20–20.31%) in SHWSD was higher than that in CN16. The amount of HMW-GS in SHWSD sharply decreased under the expression of fewer HMW-GS genes, and the LMW-GS, gliadins, and total glutenins were simultaneously increased in SHWSD in comparison with CN16. Moreover, SHWSD had higher ratios of LMWGS/glutenin and gliadin/glutenin but a lower ratio of HMW-GS/glutenin than CN16. These results provide necessary information for the utilization of SHWSD in weak-gluten wheat breeding.
文摘The core collection of red-seeded winter hexaploid triticale with different pre-harvest sprouting (PHS) resistance has been evaluated for the allelic structure of the gene VIVIPAROUS-1B (Vp-1B) with STS molecular marker. The discovered structure of the collection was as follows: 50.0% and 41.7% of the collection carries Vp-1Bа and Vp-1Bc alleles, respectively, while 8,3% possesses both of them. As a result of the seed color estimation, the collection has been divided into two groups: with dark red seeds and light red seeds. The allele Vp-1Bc has appeared to be associated with PHS resistance while Vp-1Ba with PHS susceptibility in the triticale accessions with light red seeds only. The influence of the seed color and allelic state of Vp-1B on PHS resistance in triticale is discussed.
基金Supported by National Key Research and Development Program of China(2016YFD0101802)Modern Agricultural Science and Technology Innovation Engineering Project of Hebei Province(2017038997)National Natural Science Foundation of Hebei Province(C2014106075)
文摘In order to study the roles of members of HKT gene fanfily in wheat, TaHKT2 ; 2 was isolated by using homologous cloning strategy and screening genomic BAC library. TaHKT2; 2 genes were mapped on chromosomes 7A, 7B and 7D, named as TaHKT2; 2-7A, TaHKT2; 2-7B, and TaHKT2; 2-7D, respectively. TaHKT2 ; 2 and TaHKT2 ; 1 had the same genetic structure, composed of three exons and two introns, and formed a cluster with TaHKT2 ; 1 on the phylogenetic tree of plant HKT transporters. The coding sequences of TaHKT2 ; 2-7A, TaHKT2 ; 2-7B, and TaHKT2 ; 2-7D were 1 602, 1 602 and 1 596 bp long, respectively, but TaHKT2 ;2-7D cDNA sequence was not isolated by RT-PCR in eight wheat varieties. The natural diversity of TaHKT2 ;2 genes was analyzed by cloning and sequencing from 12 wheat varieties. The results showed that TaHKT2;2-7A was found to be more diverse than TaHKT2; 2-7B and TaHKT2; 2-7D. Only a few bases changed in the alleles of TaHKT2 ; 2 genes in wheat. No amino-acid natural variation lay in the P-loops of deduced protein sequences of all alleles of TaHKT2 ; 2 in 12 wheat varieties. The identity of coding sequences was nmch higher than that of 5＇ flanking regions of TaHKT2 ; 2 genes. TaHKT2 ; 2 nfight be selected over the comse of wheat domestication and belonged to domestication gene.
文摘The wild cotton diploid species (2n = 2x = 26) are important sources of useful traits such as high fiber quality, resistance to biotic and abiotic stresses etc., which can be introgressed into the cultivated tetraploid cotton <i>Gossypium hirsutum</i> L (2n = 4x = 52), for its genetic improvement. The African wild diploid species <i>G. longicalyx</i> Hutchinson and Lee could be used as donor of the desirable traits of fiber fineness and resistance to reniform nematode. However, hybridization of wild diploid species and cultivated tetraploid cotton encounters a sterility problem of the triploid (2n = 3x = 59), mainly due to ploidy. The restoration of the fertility can be done by creating an allohexaploid (2n = 6x = 78) through the doubling with colchicine of the sterile triploid chromosomes. With this method, a synthetic allohexaploid hybrid (<i>G. hirsutum</i> × <i>G. longicalyx</i>)2 has been obtained. This genotype was studied using phenotypic, cytological and molecular (AFLP) analyses in order to confirm its hybridity and its caryotype, and also to verify the expression of the desirable traits coming from <i>G. longicalyx</i>. The studied genotype showed a quite good level of pollen fertility (83%), and apart from larger seeds and some minor seedling anomalies, most of its morphological characteristics were intermediate between the two parental species. It had 78 chromosomes, proving its hexaploid status. Molecular analysis revealed 136 AFLP loci in this hexaploid, all from <i>G. hirsutum</i> and <i>G. longicalyx</i>, demonstrating its hybrid status. In addition, the hexaploid exhibited the useful traits of <i>G. longicalyx</i> with regard to its remarkable fiber fineness and its high resistance to the reniform nematode. This allohexaploid hybrid constitutes an interesting agronomic material, which can be used as a bridge for the transfer of useful agronomic traits from wild species to varieties of <i>G. hirsutum</i>.
文摘With 17% of all crop area, wheat is the staple food for 40% of the world’s population. Improvement in bread wheat quality and yield in the context of sustainable agriculture is needed in the next decades to meet human
基金supported by the National Key R&D Program of China (2021YFC2600101)the Shenzhen Science and Technology Program (JCYJ20190814163805604 and KQTD20180411143628272)+1 种基金the Fund of the Key Laboratory of Shenzhen (ZDSYS20141118170111640)the Agricultural Science and Technology Innovation Program.
文摘Jerusalem artichoke(Helianthus tuberosus)is a global multifunctional crop.It has wide applications in the food,health,feed,and biofuel industries and in ecological protection;it also serves as a germplasm pool for breeding of the global oil crop common sunflower(Helianthus annuus).However,biological studies of Je-rusalem artichoke have been hindered by a lack of genome sequences,and its high polyploidy and large genome size have posed challenges to genome assembly.Here,we report a 21-Gb chromosome-level as-sembly of the hexaploid Jerusalem artichoke genome,which comprises 17 homologous groups,each with 6 pseudochromosomes.We found multiple large-scale chromosome rearrangements between Jerusalem artichoke and common sunflower,and our results show that the hexaploid genome of Jerusalem artichoke was formed by a hybridization event between a tetraploid and a diploid Helianthus species,followed by chromosome doubling of the hybrid,which occurred approximately 2 million years ago.Moreover,we iden-tied more copies of actively expressed genes involved in inulin metabolism and showed that these genes may still be undergoing loss of function or sub-or neofunctionalization.These genomic resources will pro-mote further biological studies,breeding improvement,and industrial utilization of Helianthus crops.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.30270804 and 30070462).
文摘It was suggested that the rapid changes of DNA sequence and gene expression oc- curred at the early stages of allopolyploid formation. In this study, we revealed the microsatellite (SSR) differences between newly formed allopolyploids and their donor parents by using 21 primer sets specific for D genome of wheat. It was indicated that rapid changes had occurred in the “shock” process of the allopolyploid formation between tetraploid wheat and Aegilops tauschii. The changes of SSR flanking sequence resulted in appearance of novel bands or disappearance of parental bands. The disappearance of the parental bands showed much higher frequencies in comparison with that of appearance of novel bands. Disappearance of the parental bands was not random. The frequency of disappearance in tetraploid wheat was much higher than in Ae. tauschii, i. e. the disappearance frequency in AABB genome was much higher than in D genome. Changes of SSR flanking sequence occurred at the early stage of F1 hybrid or just after chro- mosome doubling. From the above results, it can be inferred that SSR flanking sequence region was very active and was amenable to change in the process of polyploidization. This suggested that SSR flanking sequence probably had special biological function at the early stage of ploy- ploidization. The rapid and directional changes at the early stage of polyploidization might con- tribute to the rapid evolution of the newly formed allopolyploid and allow the divergent genomes to act in harmony.
文摘Three diploid （Triticum boeoticum, AA; Aegilops speltoides, BB and Ae. tauschii, DD）, two tetraplold （T. dlcoccoides, AABB and T. dicoccon, AABB） and one hexapioid （T. vulgare, AABBDD） varieties of wheat, which are very important In the evolution of wheat were chosen in this study. A pot experiment was carried out on the wheat under different water and nutrient conditions （i） to understand the differences in biomass, yield, water use efficiency （WUE）, and nutrient （N, P and K） use efficiency （uptake and utilization efficiency） among ploidies in the evolution of wheat; （li） to clarify the effect of water and nutrient conditions on water and nutrient use efficiency; and （ill） to assess the relationship of water and nutrient use efficiency in the evolution of wheat. Our results showed that from diploid to tetraplold then to hexaploid during the evolution of wheat, both root biomass and above-ground biomass Increased Initially and then decreased. Water consumption for transpiration decreased remarkably, correlating with the decline of the growth period, while grain yield, harvest index, WUE, N, P and K uptake efficiency, and N, P and K utilization efficiency Increased significantly. Grain yield, harvest index and WUE decreased In the same order： T. vulgare 〉 T. dicoccon 〉 T. dicoccoides 〉 Ae. tauschii 〉 Ae. speltoides 〉 T. boeoticum. Water stress significantly decreased root blomass, above-ground biomass, yield, and water consumption for transpiration by 47-52%, but remarkably Increased WUE. Increasing the nutrient supply increased wheat above-ground biomass, grain yield, harvest Index, water consumption for transpiration and WUE under different water levels, but reduced root blomass under drought conditions. Generally, water stress and low nutrient supply resulted in the lower nutrient uptake efficiency of wheat. However, water and nutrient application had no significant effects on nutrient utilization efficiency, suggesting that wheat nutrient utilization efficiency is mainly controlled by genotypes. Compared to the other two diploid wheats, Ae. squarrosa （DD） had significant higher WUE and nutrient utilization efficiency, Indicating that the D genome may carry genes controlling high efficient utilization of water and nutrient. Significant relation- ships were found between WUE and N, P and K utilization efficiency.
