Drought is a major constraint in many wheat( Triticum aestivum L.) production regions. Quantitative trait loci (QTLs) conditioning drought tolerance at stages of germination and seedling in wheat were identified in...Drought is a major constraint in many wheat( Triticum aestivum L.) production regions. Quantitative trait loci (QTLs) conditioning drought tolerance at stages of germination and seedling in wheat were identified in a double haploid (DH) population derived from the cross, Hanxuan10×Lumai14, using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. Interval mapping analysis revealed that QTLs for drought tolerance at germination stage were located on chromosomes 1B, 2B, 5A, 6B, 7A and 7B, respectively, and the most effective QTL was mapped on chromosome 2B, explaining 27.2% of phenotypic variance. The QTLs for drought tolerance at seedling stage were located on 1B, 3B and 7B, respectively, and the most effective QTL was mapped on chromosome 3B, explaining 21.6% of phenotypic variance. Their positions were different from those of QTLs conferring drought tolerance at germination stage, indicating that drought tolerance at germination stage and seedling stage was controlled by different loci. Most of the identified QTLs explained 18% or more of phenotypic variance for drought tolerance at germination and seedling stage, and would be useful in future for marker assisted selection programs and cultivar improvement.展开更多
Fluorescent in situ hybridization (FISH) was used to investigate the chromosomal location of 18S-5.8S-26S rDNA loci in Thinopyrum intermedium (Host) Barkworth et Dewey (2n=6x=42). In all accessions and individuals stu...Fluorescent in situ hybridization (FISH) was used to investigate the chromosomal location of 18S-5.8S-26S rDNA loci in Thinopyrum intermedium (Host) Barkworth et Dewey (2n=6x=42). In all accessions and individuals studied, 3 or 4 pairs of major loci were detected. Subsequent genomic in situhybddization (GISH) analyses revealed that one pair was located on the ends of the short arms of one pair of homologous chromosomes of the St genome, while the other 2 or 3 pairs of major loci were located in the E genomes (including the E^o and E^b). It is suggested that 2 to 3 pairs of major loci were probably lost during the evolution of this hexaploid species. The variation in rDNA positions and copy numbers between the diploid donors and Th. interrnedium, as well as the diversity among the accessions of Th. intermedium confirmed that the rDNA gene family conveyed the characters of DNA mobile elements. The internal transcribed spacer (ITS) regions of the rDNA in Th. intermedium were also investigated. Sequence data of seven positive clones from one individual suggested high degree of individual heterogeneity exists among ITS repeats. Phylogenetic analyses showed that there were two distinct types of ITS sequences in Th. intermedium, one with homology to that of Pseudoroegneria species (St genome) and the other to that of the E genome diploid species. This showed that the ITS paralogues in Th. intermedium have not been uniformly homogenized by concerted evolution. The limitation of using the chromosomal location of rDNA loci for phylogenetic analysis is discussed.展开更多
: Wide cross and molecular cytogenetic methods were used to transfer the powdery mildew resistance gene from Thinopyron intermedium(Host) Barkworth & DR Dewey to wheat. Among the progeny of crossing common wheat (...: Wide cross and molecular cytogenetic methods were used to transfer the powdery mildew resistance gene from Thinopyron intermedium(Host) Barkworth & DR Dewey to wheat. Among the progeny of crossing common wheat (Triticum aestivum L.) Yannong 15 with Th. intermedium, a partial amphiploid E990256, with resistance to powdery mildew, was developed. It had 56 chromosomes and could form 28 bivalents in pollen mother cells at metaphase I of meiosis. Resistance verification by race 15 at the seedling stage and by mixed strains of Erysiphales gramnis DC. f. sp. tritici Em. Marchal at the adult stage showed it was immune to powdery mildew at both stages. Gene postulation via 21 isolates of E. gramnis f. sp. tritici and 29 differential hosts showed it was nearly immune to all the isolates used, and its resistance pattern was different from all the mildew resistance genes used, which indicated it probably contained a new resistance gene to powdery mildew. Biochemical verification showed it might convey different Th. intermedium chromosomes from those of the wheat- Th. intermedium partial amphiploids Zhong 1–5. Genomic in situ hybridization analysis by using St genomic DNA as the probe showed E990256 contained a recombination genome of St and E.展开更多
文摘Drought is a major constraint in many wheat( Triticum aestivum L.) production regions. Quantitative trait loci (QTLs) conditioning drought tolerance at stages of germination and seedling in wheat were identified in a double haploid (DH) population derived from the cross, Hanxuan10×Lumai14, using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. Interval mapping analysis revealed that QTLs for drought tolerance at germination stage were located on chromosomes 1B, 2B, 5A, 6B, 7A and 7B, respectively, and the most effective QTL was mapped on chromosome 2B, explaining 27.2% of phenotypic variance. The QTLs for drought tolerance at seedling stage were located on 1B, 3B and 7B, respectively, and the most effective QTL was mapped on chromosome 3B, explaining 21.6% of phenotypic variance. Their positions were different from those of QTLs conferring drought tolerance at germination stage, indicating that drought tolerance at germination stage and seedling stage was controlled by different loci. Most of the identified QTLs explained 18% or more of phenotypic variance for drought tolerance at germination and seedling stage, and would be useful in future for marker assisted selection programs and cultivar improvement.
文摘Fluorescent in situ hybridization (FISH) was used to investigate the chromosomal location of 18S-5.8S-26S rDNA loci in Thinopyrum intermedium (Host) Barkworth et Dewey (2n=6x=42). In all accessions and individuals studied, 3 or 4 pairs of major loci were detected. Subsequent genomic in situhybddization (GISH) analyses revealed that one pair was located on the ends of the short arms of one pair of homologous chromosomes of the St genome, while the other 2 or 3 pairs of major loci were located in the E genomes (including the E^o and E^b). It is suggested that 2 to 3 pairs of major loci were probably lost during the evolution of this hexaploid species. The variation in rDNA positions and copy numbers between the diploid donors and Th. interrnedium, as well as the diversity among the accessions of Th. intermedium confirmed that the rDNA gene family conveyed the characters of DNA mobile elements. The internal transcribed spacer (ITS) regions of the rDNA in Th. intermedium were also investigated. Sequence data of seven positive clones from one individual suggested high degree of individual heterogeneity exists among ITS repeats. Phylogenetic analyses showed that there were two distinct types of ITS sequences in Th. intermedium, one with homology to that of Pseudoroegneria species (St genome) and the other to that of the E genome diploid species. This showed that the ITS paralogues in Th. intermedium have not been uniformly homogenized by concerted evolution. The limitation of using the chromosomal location of rDNA loci for phylogenetic analysis is discussed.
文摘: Wide cross and molecular cytogenetic methods were used to transfer the powdery mildew resistance gene from Thinopyron intermedium(Host) Barkworth & DR Dewey to wheat. Among the progeny of crossing common wheat (Triticum aestivum L.) Yannong 15 with Th. intermedium, a partial amphiploid E990256, with resistance to powdery mildew, was developed. It had 56 chromosomes and could form 28 bivalents in pollen mother cells at metaphase I of meiosis. Resistance verification by race 15 at the seedling stage and by mixed strains of Erysiphales gramnis DC. f. sp. tritici Em. Marchal at the adult stage showed it was immune to powdery mildew at both stages. Gene postulation via 21 isolates of E. gramnis f. sp. tritici and 29 differential hosts showed it was nearly immune to all the isolates used, and its resistance pattern was different from all the mildew resistance genes used, which indicated it probably contained a new resistance gene to powdery mildew. Biochemical verification showed it might convey different Th. intermedium chromosomes from those of the wheat- Th. intermedium partial amphiploids Zhong 1–5. Genomic in situ hybridization analysis by using St genomic DNA as the probe showed E990256 contained a recombination genome of St and E.
