Molecular variation in Rhynchosporium secalis isolates obtained from hotspots
- 61 Downloads
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.
Additional keywordsHordeum vulgare fungal plant pathogen disease
Unable to display preview. Download preview PDF.
- Ali SM, Mayfield AH, Clare BG (1976) Pathogenicity of 203 isolates of Rhynchosporium secalis on 21 barley cultivars. Plant Pathology 9, 153–443.Google Scholar
- Armstrong JS, Gibbs AJ, Peakall R, Weiler G (1994) ‘The RAPDistance package’ http://life.anu.edu.au/molecular/software/rapd.htmlGoogle Scholar
- Baayen RP, O'Donnell K, Bonants PJM, Cigelnik E, Kroon LPNM, Roebroeck EJA, Waalwijk C (2000) Gene genealogies and AFLP analyses in the Fusarium oxysporum complex identify monophyletic and nonmonophyletic formae speciales causing wilt and root disease. Phytopathology 90, 891–900.CrossRefPubMedGoogle Scholar
- Felsenstein J (1993) PHYLIP—Phylogeny Inference Package Version 3.5c.Google Scholar
- Goodwin SB, Allard RW, Hardy SA, Webster RK (1992) Heirarchical structure of pathogen variation among Rhynchosporium secalis populations in Idaho and Oregon. Canadian Journal of Botany 70, 810–817.Google Scholar
- Jaccard P (1901) Etude comparative de la distribution florale dans une portion des Alpes et des Jura. Bulletin de la Société Vaudoise des Sciences Naturelles 37, 547–579.Google Scholar
- Jaccard P (1908) Nouvelles recherches sur la distribution florale. Bulletin de la Société Vaudoise des Sciences Naturelles 44, 223–270.Google Scholar
- Newton AC, Searle J, Guy DC, Hackett CA, Cooke DEL (2001) Variability in pathotype, aggressiveness, RAPD profile, and rDNA ITS1 sequences of UK isolates of Rhynchosporium secalis. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz 108, 446–458.Google Scholar
- Pringle RB, Sheffer RP (1963) Purification of the selective toxin of Periconia circinata. Phytopathology 53, 758–787Google Scholar
- Shipton WA, Boyd WJR, Ali SM (1974) Scald of barley. Review of Plant Pathology 53, 839–861.Google Scholar
- Yap IV, Nelson RJ (1996) ‘Winboot: a program for performing bootstrap analysis of binary data to determine the confidence limits of UPGMA-based dendrograms.’ (International Rice Research Institute: Manila, Philippines)Google Scholar