Evaluation of Major and Environmentally Driven Genes for Resistance in Pakistani Wheat Landraces and their Prospected Potential against Yellow Rust

Yellow rust is caused by Pst ( Puccinia striiformis tritici ), the most devastating wheat disease with continuous challenge of emerging virulences breaking vertical resistance worldwide resulting in epidemics. Vertical resistance genes incorporation is a sustainable, economical and environment-friendly approach to control rust diseases. Wheat landraces (WLR) acquired vertical resistance through long time exposure of host-pathogen survival competition in a specific area having unique agronomic traits, genetic base and resistance against biotic and abiotic agents can be an exploitable commodity for future food production. Fifty Pakistani WLRs already with known vertical resistance were screened against 7 potential Pakistani Pst races at seedling stage under glasshouse conditions to postulate resistance genes. Resistance magnitude was compared among the landraces. Six genes Yr1, Yr8, Yr9, Yr43, Yr44, and YrTr1 were successfully postulated either singly or in combination along with unidentified genes in 45 landraces. Pakistani Pst races are avirulent to  Yr5, Yr10 ,  Yr15 ,  Yr24 ,  Yr32, YrSp and YrTye . Most frequently postulated genes are Yr44 found in 22 genotypes, YrTr1 in 21, Yr9 in 19, Yr43 in 18, Yr8 and Yr1 in 14 wheat landraces. Multiple Yr gene pyramiding was observed in (B-74, B-281, B-530) with the presence of Yr8, Yr9, Yr43, Yr44,  and  YrTr1 and single gene were postulated from 12 genotypes. WLRs (B-03, B-158, B-160, B-171) reaction was immune showing presence of novel Yr genes. The study provides information regarding yellow rust resistance genes originated independently against localized Pst races with desirable agronomic traits since long and can be an option for food security in changing environmental challenges.