Abstract only

Stem rust of wheat, caused by Puccinia graminis f. sp. triticii (Pgt), is a major threat to global wheat production. Detection of Pgt pathotype Ug99 (TTKSK) in Kenya rendered Sr31 and many other stem rust resistance genes ineffective. An Indian wheat cultivar VL404 produced high infection type (IT3+) against the prevalent Pgt pathotypes of Australia. It showed a low seedling infection type (IT; to 2-) when tested against TTKSK and TTKST in the USA. A recombinant inbred line population (RIL) from the cross VL404/ WL711 was phenotyped using the Pgt pathotype TTKST. Chi-squared analysis conformed to segregation at a single locus and the locus was temporarily named as SrVL. Molecular mapping using DArT and SSR markers placed it in the long arm of chromosome 2B flanked by markers gwm120 and wmc175 at 3.3Cm each proximally and distally. Comparison of infection type and relative position of markers in chromosome 2BL led us to conclude that SrVL was Sr28. Virulence for Sr28 has been reported in all wheat growing areas of the world. The identification of flanking markers in this study would enable pyramiding of Sr28 with molecularly tagged stem rust resistance genes Sr22, Sr26, Sr33, Sr39, Sr40 and Sr50 that are effective against a wide range of Pgt pathotypes. The Australian wheat genotypes Janz and CSP44 also carry Sr28. The presence of Sr28 in Janz and CSP44 was traced back to LV-Rus parent of Kota.

Global Wheat Program

English

Lucia Segura

INT2843