Virulence and molecular analysis of atypical pathotypes of yellow rust pathogen in India

Wheat and barley yellow rust pathogens, Puccinia striiformis f. sp. tritici (Pst) and P. striiformis f. sp. hordei (Psh), respectively, can change quickly in virulence. The present study was conducted using host differentials and microsatellite marker assay to determine the relationship of two newly detected atypical Pst pathotypes (6S0 and 7S0) with known pathotypes from wheat (46S103, 47S103, 46S119, 111S68 and 79S68) and barley (0S0-1, 4S0, 0S0 and 1S0). A set of 21 SSR markers were used to determine inter-relationship among these pathotypes. In toto, 79 alleles were detected across the 21 loci. Six markers (RJ22, SUNIPst9-40, SUNIPst09-48, SUNIPst10-48, SUNIPst11-01 and SUNIPst16-10) were found highly informative. The polymorphism information content (PIC) values of these markers were > 0.69. These markers provided useful information on genetic divergence of newly emerged Pst pathotypes. Principle component analysis (PCoA) explained 62.91% variation among the analysed pathotypes. The molecular variation studies showed that new Pst pathotypes (6S0 and 7S0) are more close to known pathotypes from barley than from wheat. The major distinction in term of virulence was that pathotype 7S0 possessed extra virulence for Yr1 and lacked virulence for rpsTr1 and rpsTr2.