Identification of Sources of Resistance toPhoma medicaginisIsolates inMedicago truncatulaSARDI Core Collection Accessions, and Multigene Differentiation of Isolates

Ellwood, S.R., Kamphuis, L.G. and Oliver, R.P. (2006) Identification of Sources of Resistance toPhoma medicaginisIsolates inMedicago truncatulaSARDI Core Collection Accessions, and Multigene Differentiation of Isolates. Phytopathology, 96 (12). pp. 1330-1336.

Abstract

Phoma medicaginis is a necrotrophic fungal pathogen, commonly found infecting the annual medic Medicago truncatula. To differentiate eight P. medicaginis isolates, five gene regions were examined: actin, β-tubulin, calmodulin, translation elongation factor I-α (EF-1α), and the internal transcribed spacer ribosomal DNA. Sequence comparisons showed that specimens isolated from M. truncatula in Western Australia formed a group that was consistently different from, but allied to, a P. medicaginis var. medicaginis type specimen. EP-1α contained a hypervariable 55-bp repeat unit, which forms the basis of a rapid polymerase chain reaction-based method of reliably distinguishing isolates. Characterization of three isolates showed that all exhibited a narrow host range. causing disease only in M. sativa and M. truncatula among eight commonly cultivated legume species sampled. Infection of 86 M. truncatula single-seeded accessions showed a continuous distribution in disease phenotypes, with the majority of accessions susceptible. On a 1-to-5 disease reaction scale increasing in severity, individual fungal isolates showed means of 2.6 to 3.2. and scores ranged from 1 to 4.8 among accessions. The results presented here suggest that M. truncatula harbors specific and diverse sources of resistance to individual P. medicaginis genotypes.

Publication Type:	Journal Article
Murdoch Affiliation:	Australian Centre for Necrotrophic Fungal Pathogens Western Australian State Agricultural Biotechnology Centre
Publisher:	The American Phytopathological Society
Copyright:	© 2006 The American Phytopathological Society.
URI:	http://researchrepository.murdoch.edu.au/id/eprint/11271

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