Quantitative trait loci (QTL) analysis of flag leaf senescence in wheat (Triticum aestivum L.) with microsatellite DNA markers under water-stressed condition
The objective of this study was to detect quantitative trait loci (QTL) associated with drought tolerance in wheat genotypes by simple sequence repeat (SSR) markers and to provide valuable information for marker assisted selection. SSR markers linked to flag leaf senescence (FLS) was identified in two DNA pools, which were established using F2 mapping population, resulting from a cross between a drought sensitive genotype 'Variant-11' and drought tolerant genotype 'Veery'. Parents were screened initially with 34 SSR primer pairs. The linkage map was constructed with the six linked markers into one linkage group covering 82.7 cm. QTL detection with analysis of variance showed that all of the six markers were significantly associated with drought tolerance in this population. Single marker regression (SMR) analysis revealed that R-square percentage ranged from 39.3% (Xgwm339) and 12.3% (Xgwm577). Simple interval mapping (SIM) located a QTL for leaf flag senescence, between markers interval Xgwm566 and Xgwm339, while composite interval mapping (CIM) indicated a QTL location between the interval marker Xgwm296 and Xgwm566. The SSR markers can be used for the detection of QTLs quantitative trait loci linked with flag leaf senescence as indicator for drought tolerance.
Key words: Flag leaf senescence, Triticum aestivum L., SSR markers, simple interval mapping (SIM), composite interval mapping (CIM), quantitative trait loci (QTL).