Variation for isozymes and double‐stranded RNA among isolates of Puccinia striiformis and two other cereal rusts

Abstract

Gel electrophoresis was used to examine the variation in isozymes and dsRNA within and between the rust species Puccinia striiformis, P. recondita and P. hordei. No differences in isozyme phenotype were found among 29 diverse isolates of the wheat‐attacking form of P. striiformis (WYR). Smaller numbers of isolates of the barley‐attacking form (BYR) of P. recondita and of P. hordei showed similar intra‐group uniformity. There were major differences in isozyme phenotypes between the three species, while WYR and BYR differed for two of 12 enzymes. Double‐stranded RNA was detected in each species and in all 26 isolates examined. For WYR and BYR, all isolates within each group had the same or a similar phenotype. In contrast, each isolate of P. recondita and P. hordei had a unique phenotype. There were differences in dsRNA phenotypes both between the three species and between WYR and BYR. The uniformity of these rust populations and species for isozyme phenotype is contrasted with their variability in pathogenicity and with the variability in isozymes encountered in higher organisms. Uniformity may result from a feature of the biology of the rust species and populations examined, or from the relative homogeneity of the environment of biotrophic pathogens. Consistent differences in isozyme and dsRNA phenotype between the WYR and BYR isolates of P. striiformis indicate that these are two discrete populations, supporting the view that they should be recognized as f.sp. tritici and f.sp. hordei, respectively.

Study Genetic Variation Using DNA Molecular Markers and Identification Physiological Races of Wheat Stripe (yellow) Rust Puccinia striiformis f.sp tritici during 2010-2014 in Some Regions of Syria

“…4). The races, representing one area, were separated into different groups, while those related to geographically different areas clustered in same groups, and these results agree with previous studies [31,32], since the yellow rust spores can travel with air for far distance to anywhere [33], so it is more likely to be one region invaded by many different races simultaneously. Table 3 Physiological races of the fungus yellow rust on wheat registered in Syria and its pathogenicity genes during the 2011-2014.…”

Nonhost plant species as donors for resistance to pathogens with narrow host range I. Determination of nonhost status

“…Studies on variation in isozyme patterns (BURDON & MARSHALL, 1981; VAN JAARS-VELD & DU TOIT, 1984;NEWTON et al, 1985), in detergent-soluble polypeptide composition (KIM et al, 1985a,b), in mycelial morphology (NIKS, 1986) and studies on crossability (e.g. JOHNSON, 1949;HIURA, 1978;NEWTON et al, 1986) strongly suggest that formae speciales of a micro-organism species are not seldom distinct taxonomic units with restricted or no genetic exchange.…”

Estimation of the mating system in a fungal pathogen Crumenulopsis sororia (Karst.) Groves using isozyme markers

“…In addition we have data on variation for sexual incompatability loci (Burnett, 1965;Stenlid, 1985), virulence races (Roelfs and Groth, 1980), and vegetative compatibility (Anagnostakis, 1977(Anagnostakis, , 1982aRayner and Turton, 1982;Brasier, 1984) in a limited range of parasitic species. More recent analyses of isozyme variation have provided information on the origins and genetic structure of a handful of economically important pathogen populations Marshall, 1981, 1983;Burdon et a!., , 1982Bernier et a!., 1983;Old et a!., 1984; Roelfs, 1985a, 1985b;Newton and Caten, 1985). Despite these efforts, however, we remain ignorant of many aspects of the genetics of fungal pathogen populations.…”