Document Type : Original Article
Authors
Wheat Disease Research Department, Plant Pathology Research Institute, Agricultural Research Center, 12619 Giza, Egypt
Abstract
Race-specific resistance of stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) in relation to susceptibility of Egyptian wheat cultivars were investigated during two growing seasons 2017/18 and 2018/19 in Egypt. High levels of adult plant susceptibility were recorded in the second season in comparison with that of the first season. Out of 20 cultivars tested, susceptibility (S) up to 80 S was recorded with only 8 cultivars and 4 resistance genes (Yr) in the first season. However, it was recorded with 14 cultivars (reached 90 S) and 7 Yr genes (up to 80 S) in the second one. The highest susceptibility was recorded with Sids-12 and Gemmeiza-11 (90 S), followed by Misr-1 (80 S), Misr-2 (70 S), Giza-163 (60 S), Yr7 and Yr9 (80 S). Cultivars, Misr-1, Misr-2, Gemmeiza-5, Gemmeiza-12, Giza-167, and Shandweel-1, exhibiting moderate resistance (MR) in the first season, lost their resistance in the second one. Nine Yr genes Yr2, Yr4, Yr6, Yr7, Yr8, Yr9, Yr10, Yr25, Yr27, Yr32 and YrSp < /em> were postulated in cultivars through multipathotyping with the prevailing Pst races in Egypt, 64E0, 0E16, 66E0, 4E130, 2E0, 2E16, 4E0, 6E4, 70E4, PstS2, PstS3 and Triticale aggressive. Only Yr9 was present in 7 susceptible cultivars, Sids-13, Gemmeiza-7, Gemmeiza-9, Gemmeiza-10, Gemmeiza11, Gemmeiza-12, and Shandweel-1. A molecular assay using the STS marker iag95 validated the presence of Yr9 in the last-mentioned cultivars. Cultivars may have become susceptible due to the virulence to Yr9 gene, which should be restricted to use alone in wheat production.
Keywords
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