Development Of EST-PCR Markers For Wild Relatives Of Wheat

Wild-hybridization is one of the feasible ways for useful trait introgression into wheat. It is rather important to trace the chromosome or chromosome segments introduced effectively before translocation lines produce. It has been reported that the 2Ai-2 chromosome from wild grass Thinopyrum intermedium with high BYDV resistance and the 2H chromosome from Barley with pre-harvest sprouting resistance as well as starch quality improvement have been introduced respectively into wheat by wild-hybridization. And two sets of disomic addition/substitution lines produced. In this research, several 2Ai-2 and 2H-specific EST-PCR markers were developed based on the two sets of lines.According to the functional gene sequences conservation among wheat and its wild relatives Thinopyrum intermedium and Barley, we designed 120 pairs of EST primers which derived from ESTs allocated on wheat group 2 chromosomes. Most of them (90% in Thinopyrum intermedium and 95% in Barley) amplified successfully and 15 2Ai-2 specific EST-PCR markers (with a yield rate 12.5%) as well as 30 2H-specific (with a yield rate 25%) were obtained. These markers show polymorphism in 3 levels: AGE, PAGE, SSCP and could be classified into 2 types: simple polymorphism and complex polymorphism. Despite the alien chromosome specific markers, a lot of wheat group 2 chromosomes specific ones also produced.Due to the relatively large and polyploidy wheat genome, It was of great challenge to develop alien chromosomes-specific EST-PCR markers in wheat background, even when these chromosomes were close relative with wheat chromosomes. Intron-Flanking method plus a "triple-levels -separation system"is the best solution so far. The result of this research has proved this effective. These alien chromosome-specific EST-markers would find ready use in screening for new wheat germplasm.