abstract
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Detection and characterization of changes in virulence patterns of pathogen’s populations is a prelude to effective management of wheat rusts. Such information is useful for the identification of sources of resistance, pre-emptive breeding and judicious deployment of resistant wheat cultivars. During 2013-14, three new Yr9-virulent pathotypes (110S119, 238S119 and 110S84) of Puccinia striiformis f. sp. tritici( Pst) possessing combined virulence to Strubes Dickkopf (Yr2, Yr3a, Yr4a) and Suwon92xOmar (YrSU) were detected in India. These pathotypes were more aggressive and virulent than those reported earlier. Riebesel 47/51 (Yr2,Yr9) and Hobbit (Yr14) hitherto resistant to Indian Pst populations, became susceptible to 238S119 and 110S119, respectively. Moreover, bread wheat cultivar HD2967, currently occupying 10-12 million hectares area, showed high level of susceptibility to these pathotypes. Stripe rust resistance genes, Yr1, Yr5, Yr10, Yr15, Yr24, Yr28 andYrSP were found effective against the new pathotypes. Indian bread wheat germplasm comprising 56 newly released cultivars and 64 advanced lines (2016-17) were evaluated under controlled conditions at seedling stage for resistance to the three new and two other known Yr9-virulent pathotypes 46S119 and 78S84. None of the cultivars was resistant to the new pathotypes. Cultivars DBW88, DPW621-50, HD3043, HD3059, HD3171, HS507, HS542, HS562, MACS6478, PBW723, WH1021 and WH1105, resistant to the erstwhile prevalent pathotypes 46S119 and 78S84, showed susceptibility to the new pathotypes. However, 11 advanced bread wheat lines viz. DBW246, HS645, PBW752, PBW757, PBW777, PBW779, PBW780, UP2993, VL1012, VL3013 and WH1233 were found resistant to all the test pathotypes. These lines can be deployed for cultivation directly or used in stripe rust resistance breeding programme.