Location: Hard Winter Wheat Genetics Research Unit
Title: Mapping and QTL analysis of drought tolerance in a spring wheat population using AFLP and DArt markers Authors
|Alexander, Lauren -|
|Kirigwi, Francis -|
|Fritz, Allan -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 6, 2011
Publication Date: N/A
Interpretive Summary: Water is the main limiting factor in crop production and significantly affects yields and quality in wheat production. However, breeding for drought tolerance is difficult because tolerance can be measured by many traits and is regulated by many genes across the genome. This work reports on further efforts to try to identify gene regions in the wheat genome that are involved in drought tolerance. The mapping techniques used in this study are more efficient at finding important regions in the genome. Twelve wheat chromosomes, 1D, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6D, 7A, and 7B, have regions associated with drought tolerance, while four more DNA markers were found linked with a drought tolerance with the one major locus on 4AL. One of the new markers could explain almost 1/3 of the differences between the experimental lines for grain fill rate and for yield. Plant breeders are using the markers to help move this region on 4AL into breeding lines to improve crop performance in drought conditions.
Technical Abstract: Water availability is commonly the most limiting factor to crop production. This study was conducted to map quantitative trait loci (QTL) involved in drought tolerance in wheat (Triticum aestivum L.) to enable their use for marker assisted selection (MAS) in breeding. Using amplified fragment length polymorphisms (AFLP) and Diversity Array Technology (DArT) markers, a population of 122 F7-derived recombinant inbred lines from a cross between Dharwar Dry and Sitta was reanalyzed in an effort to scan the genome for previously unknown QTL associated with drought tolerance traits and also to further saturate known QTL regions. A linkage map of 48 groups was created from the combined data of DArT markers, AFLP, and previously reported SSR markers. QTL were found in 24 of the 48 groups. Groups could be anchored on chromosomes 1D, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6D, 7A, and 7B. While four additional AFLP markers were added to the major QTL for drought tolerance on chromosome 4AL, a second major locus was found on chromosome 7B. The locus QDt.ksu-7B spans 34.7 cM and associated SSR marker Xbarc172 and DArT marker XwPt-4230 explained 11.9% and AFLP marker XGTG284 explained 10.7% of the variation for harvest index under reduced irrigation in 1999. XwPt-6463 explained 11.9 and 11.2% of the variation for drought susceptibility index for spike number and yield, respectively. The locus QDt.ksu-4A, now spans 21.9 cM and AFLP marker XCCGA110 explained 27.8 % and 39.9 % of the variation for grain fill rate and yield under reduced irrigation in 1999, respectively. These markers can now be used in marker assisted selection to improve drought tolerance in wheat.