Pyramiding of stripe rust resistance genes in bread wheat (Triticum aestivum L.
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Date
2020-03
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Sher-e-Kashmir University of Agricultural Sciences and Technology Jammu, J&K
Abstract
Stripe or yellow rust of wheat caused by Puccinia striiformis westend f. sp. tritici is devastating foliar disease and is considered of immense importance in cool and humid wheat growing parts of the world. The present study was undertaken to characterization of available variability of Yr genes, pyramiding of effective Yr genes in adapted wheat genotypes and to identify wheat lines carrying effective Yr gene using molecular marker assisted selection. The field studies revealed 15 genotypes viz: PBW 750, PBW 752, PBW 779, PBW 780, JAUW 672, WH 1184, HI 1619, 13th HTWYT 719, 25th HRWSN 2105, 47th IBWSN 1185, 32nd SAWSN 3011, HD 3086, 22nd SAWYT 316, PBW 763 and PBW 801 exhibiting resistant reaction with Average Coefficient of Infection (ACI) ranging from 0.45 to 2.77. The molecular marker validation of these genotypes using molecular markers confirmed the presence of combination of effective Yr genes. The genotypes PBW780 and 25th HRWSN 2105 had 7 Yr genes showing resistant phenotypes, suggesting that these genotypes are excellent source of effective stripe rust resistance genes.
To pyramid effective Yr genes in adapted wheat genotypes resistant plants were selected in segregating and backcross populations using molecular markers. In F4 generation, three plants having 4 different Yr gene combinations, eight plants with 3 different Yr gene combinations and sixteen plants with 2 Yr genes combinations in pyramided form were identified. In double cross BC1F2 (set A) plant no. 2, 35, 42 and 46 were found to contain both the effective genes Yr10 and Yr15 in homozygous state. Plant nos. 7, 26 and 41 had both the genes in homozygous state in set B whereas in set C, plant nos. 7, 11 and 25 were found to contain both the effective Yr genes in homozygous state. Stripe rust resistant gene Yr5, Yr10 and Yr15 were identified imparting resistance alone and or in combination with other Yr genes. Other effective combinations against present yellow rust race prevalent in Jammu region included genes Yr 17, Yr18, Yr36 and Yr40 in different combinations.
Analysis of variance for coefficient of infection (CI) values among 41 genotypes expressed year specific disease responses indicating a strong Genotype x Environment (G x E) interactions. Analysis of six basic generations revealed the significant differences among the generations of all the three crosses for all the traits. This indicated sufficient diversity among the materials under study. Generation mean analysis studies of three crosses showed that additive and dominance, as well as epistatic genetic effects, are involved in the inheritance of durable stripe rust resistance. The significance of scaling tests (A, B, C and D) indicated appreciable amount of epistasis present in different characters of the three crosses under study.
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Preferred for your work___ Wheat, Stripe rust, Yr genes, Pyramiding, MAS, additive, dominance and epistatic gene effects.