ARS | Publication request: Molecular,genetic, and virulence diversity of the rice blast pathogen in the United States

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 27, 2002
Publication Date: September 11, 2002
Citation: Correll, J.C., Guerber, J.C., Jia, Y., Lee, F.N. 2002. Molecular,genetic, and virulence diversity of the rice blast pathogen in the United States[abstract]. Proceedings of the Third International Rice Blast Conference. p. 102.

Technical Abstract: Isolates of Pyricularia grisea have been recovered from rice in the United States over the past 30 years and examined for vegetative compatibility, MGR586 DNA fingerprint diversity, mating type, and virulence. The collection represents archived and contemporary field isolates which occur throughout the United States. Complementary nitrate non-utilizing (nit) or sulfate non-utilizing (sul) mutants were used to assess vegetative compatibility in P. grisea. Distinct vegetative incompatibility barriers allowed the unambiguous assignment of isolates to distinct vegetative compatibility groups (VCGs). Four VCGs were identified and there was a complete correspondence between VCG, MGR586 lineage, and mating type among contemporary isolates (i.e., those collected after 1990). The strict association of independent markers during this sample period was consistent with a strictly asexual mode of reproduction. However, when archived isolates were examined, several different MGR586 lineages were nested within some VCGs. Among the four common MGR586 lineages, virulence changes appear to occur much more frequently among isolates in certain MGR586 lineages. The frequency of these "race-shift" changes and the molecular mechanism which allows isolates to overcome some resistance genes is being investigated.