Efficiency of Yellow Rust Resistance Genes Yr5, Yr10, Yr15 and YrSp in Improving the Two Egyptian Bread Wheat Cultivars Sids 12 and Gemmeiza 11

Document Type : Original Article

Authors

1 Wheat Research Department, Field Crops Research Institute (FCRI), Agriculture Research Centre (ARC), Egypt

2 Wheat Diseases Department, Plant Pathology Research Institute (PPRI), Agricultural Research Center (ARC), Giza, Egypt

Abstract

A FIELD and greenhouse study was conducted at Sakha Agricultural Research Station during 2015-2020 wheat seasons to enhance stripe rust resistance of the two Egyptian bread wheat cultivars Sids 12 and Gemmeiza 11 using the four monogenic lines Yr5, 10, 15 and Sp. The two wheat cultivars were crossed to the four monogenic lines to obtain eight F1 hybrids then selfed to produce F2 populations and selected F3 families. In the field, parents, F1, F2, F3, and differential genotypes were inoculated with a mixture of predominating pathotypes of the wheat stripe rust pathogen Puccinia striiformis f. sp tritici (Pst). Evaluation of the monogenic lines indicated that wheat genotypes carrying Yr5 and Yr15, at both seedling and adult plant stages exhibited high resistance to the Pst races. F1 field response confirmed that the four tested Yr genes are effective against the tested stripe rust races and resistant reaction is dominating over susceptibility. Segregation ratios of the eight F2 crosses indicated that the cultivars differ in three, two, or one genes with the monogenic lines. Average coefficient of infection recorded the lowest mean values for F2 crosses with Yr5 and Yr15 in both cultivars indicating that the two genes shifted the F2 population means toward resistance more than Yr10 and YrSp. Efficacy of the four genes can be arranged in the following order Yr5 ˃Yr15 ˃YrSp ˃Yr10 with the Sids 12 background and Yr5 ˃Yr15 ˃Yr10 ˃YrSp < /em> with the Gemmeiza 11 background. Out of the tested 63 F3 families, the highest percentage of completely resistant plants were recorded with the Yr5 crosses (35-40%) followed by Yr10 cross (34%) with Gemmeiza 11 and then the Yr15 cross (26%) with Sids 12. Two of the F3 families from Yr5 crosses were phenotypically closer to the recipient cultivars that were completely resistant and hence may have Yr5 gene in homozygous state. The promising resistant lines derived from both cultivars will be evaluated for yield and quality characteristics during the next season. Based on our results, pyramiding combinations of the three effective genes Yr5, Yr10 and Yr15 in one wheat background is expected to enhance resistance for the dominating stripe rust races in Egypt.

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