Marker Assisted Selection for Pyramiding Leaf Rust Resistance Gene in Wheat

Abstract

Bread wheat (Triticum aestivum L. em. Thell.) is the second largest grown newlinecrop in India and the most important component of national food security. The newlineproduction of wheat oscillates owing to the biotic and abiotic stresses faced by the crop. newlineWhile the abiotic stresses are a consequence of global changing climate, the biotic newlinestresses are manageable through genetic means. Wheat generally suffers from the newlinediseases caused by fungal pathogens in the tropics, especially, the three rusts viz., leaf newlinerust, stem rust and stripe rust, caused by Puccinia spp. Of the three, leaf rust disease newlinecaused by Puccinia recondita Rob. Ex Desm f.sp. tritici (syn P. triticina), is considered newlineto be one of the most devastating pathogens that is prevalent in every agro-ecological newlinezone where wheat is grown. newlineThe present study, already mapped RAPD marker (S3450) linked to the genes newlineLr48 was validated for the amplification of the critical marker fragments in developed newlinepopulation (CSP44+Lr48 X Agra Local). Marker, S3450 amplified polymorphic newlinefragment in each of the ten leaf rust resistant F2 plants, while the fragment was absent in newlineall the ten leaf rust susceptible F2 plants. newline newlineThe present study was conducted to tag an adult plant resistance gene Lr48 newlineusing microsatellite (SSR) markers and its subsequent validation. This was made newlinepossible by crossing two wheat cultivars, one of which carried the gene Lr48 (CSP44), newlinethereby being resistant to leaf rust and the other cultivar that did not carry the gene Lr48 newline(Agra Local). The F2 population of CSP44 X Agra Local segregated into 61 resistant newlineplants and 191 susceptible plants indicating monogenic segregation (and#967;2 newline1:3 = 0.084; P = newline0.772). F3 families raised from all resistant F2 plants were homozygous resistant, newlinewhereas those from susceptible F2 plants were classified as 126 segregating and 65 newlinehomozygous susceptible. The overall F2 ratio confirmed single gene segregation (and#967;2 newline1:2:1 = 0.023; P = 0.878).