Evaluation of differentials and near isogenic lines with known stripe rust resistance gene for durability of resistance.

摘要

Three international stripe rust differentials, Heines VII (Yr2), Vilmorin 23 (Yr3) and Hybrid 46 (Yr4) and 16 near isogenic lines (NILs) in wheat cv. Avocet background, each carrying a known stripe rust resistance gene, were assessed for stripe rust severity in Punjab, India, from 1999 to 2005, under the epiphytotics of 4 stripe rust (Puccinia striiformis) races. Genes Yr5, Yr10, Yr15 and Yr25 remained free from stripe rust from 1999-2005 indicating the effectiveness of these genes. The NIL carrying gene Yr9 showed increase in stripe rust severity from 30S during 1999-2000 to 70S from 2001-05, suggesting an establishment of virulence on Yr9 during this period and rendering it ineffective. The genes Yr8, Yr24 and Yr26 remained free from stripe rust during 1999-2000, but displayed disease severity ranging from 10MR to 20MR/20S in subsequent years suggesting the occurrence of virulence for these genes. Genes Yr1, Yr2, Yr3, Yr4, Yr12, Yr17, Yr18, Yr24, Yr26 and Yr27 were partially effective during the test years and there was no variation in their disease reaction and thus can be considered to possess durable resistance.