Abstract

The grain-filling rate (GFR) plays an important role in determining grain yield. An F₂population of wheat was developed from a cross between the 2 wheat cultivars, Ksu106 (heat-tolerant) and Yecora Rojo (heat-sensitive). The parents and 205 F₂plants were planted on the 20^th of January during the winter season of 2009 to evaluate heat tolerance during the grain-filling period. The sowing date in the present investigation represents the heat stress conditions in Saudi Arabia. Bulked – segregant analyses (BSA) was used in conjunction with simple sequence repeats (SSR) analysis to find markers linked to genes of heat tolerance. Composite interval mapping was used for mapping quantitative trait loci (QTL). The results reveal that 12 SSR markers: Wmc24, Wmc168, Wmc326, Xgwm30, Xgwm456, Wmc25, Wmc44,Wmc94, Wmc161, Wmc273, Wmc327 and Xgwm566 were linked to GFR by QTLs analysis of the F₂ population. The results show that regression analysis for the relationship between the 12 markers and the phenotypes of F₂ individuals were highly significant. The results demonstrate that SSR markers combined with bulked segregant analysis could be used to identify molecular markers linked to the grain filling rate as an indicator for heat tolerance in wheat.

Key words: Grain filling rate, QTL analysis, SSR marker, wheat.

Abbreviation

BSA, Bulked segregant analysis; CIM, composite interval mapping;GFR, grain filling rate; QTL, quantitative trait loci; SSR, simple sequence repeats