Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/1997
Publication Date: N/A
Citation: N/A Interpretive Summary: Barley yellow dwarf virus (BYDV) is the major viral pathogen of wheat in Indiana, the US and world. Because there are no effective BYDV resistance or tolerance genes in wheat BYDV resistance has been achieved by replacing the wheat 7D chromosome with a complete group 7 chromosome from Thinopyrum intermedium, a related wheatgrass. To localize BYDV resistance, a detailed molecular genetic analysis was done on the group 7 Th. intermedium (alien) chromosome to determine its structural organization. Wheat group 7 DNA markers and rye-specific repetitive sequences used in the analysis showed that the alien chromosome in the wheat line has distinguishing features. DNA markers present in group 7 chromosomes of wheat are present in this alien chromosome and maybe in the same order along the chromosome. A rye chromosome repetitive sequence family was present at the end of the long arm as determined by genomic DNA and chromosome analyses but was not present in the wheat chromosomes. Further analysis indicated that this alien chromosome does not contain whole segments from the rye genome. The alien chromosome is more similar to the wheat group 7A and 7D chromosomes rather than 7B albeit with some differences on the short arm as determined by DNA molecular marker analysis. This study shows that DNA markers which are mapped in wheat can be used to analyze gene position on this alien chromosome. We have also identified the molecular tools to easily ascertain when this BYDV resistance trait has been incorporated into elite soft red winter wheat lines. The results of this research are quite significant because this has now provided us and other researchers with the necessary information and tools to determine where BYDV resistance, and potentially other valuaable traits, are located in the Thinopyrum genome.
Technical Abstract: Barley Yellow Dwarf Virus (BYDV) resistance in soft red winter wheat (SRWW) cultivars has been achieved by substituting a group 7 chromosome from Thinopyrum intermedium for chromosome 7D. To localize BYDV resistance, a detailed molecular genetic analysis was done on the alien group 7 Th. intermedium chromosome to determine its structural organization. Triticeae egroup 7 RFLP markers and rye-specific repetitive sequences used in the analysis showed that the alien chromosome in the P29 substitution line has distinguishing features. The 350-480 bp rye telomeric sequence family was present on the long arm as determined by Southern and fluorescence in situ hybridization. However, further analysis using rye dispersed repetitive sequences indicated that this alien chromosome does not contain introgressed segments from the rye genome. The alien chromosome is homoeologous to wheat 7A and 7D as determined by RFLP analysis. Presence of fthe waxy gene on 7A, 7B and 7D chromosomes but its absence on the alien chromosome in P29 suggest some internal structural differences on the short arm between Th. intermedium and wheat group 7 chromosomes. The identification of rye telomeric sequences on the alien Thinopyrum chromosome and the homoeology to wheat chromosomes 7A and 7D provide the necessary information and tools to analyze smaller segments of the Thinopyrum chromosome and localize BYDV resistance in SRWW cultivars.