Abstract
A unique sampling strategy was used to search for genetic similarity among isolates of Rhynchosporium secalis, the causal agent of leaf scald of barley. A field of barley cv. Skiff with discrete ‘hotspots’ of leaf scald was identified and infected leaves were collected for this study. The isolates were genotyped using amplified fragment length polymorphism (AFLP) analysis. In contrast to previous reports of high diversity of R. secalis isolates in areas of only 1 m2, we found close genetic similarity between isolates from the same hotspot as determined by AFLP marker alleles, with a higher level of variation between isolates from different hotspots. A UPGMA phenogram showed that most isolates clustered with members of the same hotspot. This pattern is consistent with the inoculum source for the hotspots being airborne ascospores or wind-dispersed conidia from a local founder population, borne in splash-created aerosols. AFLP variation within hotspots suggests a high rate of mutation within a few cycles of fungal infection. A collection of isolates from cv. Skiff plots in a straw-inoculated disease nursery 60 km from the hotspot field was fingerprinted with AFLPs for comparison and was found to have much greater genotypic diversity.
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Williams, K., Donnellan, S., Smyl, C. et al. Molecular variation in Rhynchosporium secalis isolates obtained from hotspots. Australasian Plant Pathology 32, 257–262 (2003). https://doi.org/10.1071/AP03008
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DOI: https://doi.org/10.1071/AP03008