Studies on the genetic diversity of Pyricularia grisea: a molecular approach for management of rice blast
1996
Sivaraj, R. | Gnanamanickam, S.S. | Levy, M.
MGR-DNA fingerprints (EcoRI restriction fragment profiles that hybridize to the homologous dispersed repeated sequence MGR586) were used to determine the genealogical relationships among field isolates of the blast fungus in southern India. The genetic diversity in the sampling indicates that the pathogen population in southern India is composed of 29 distinct clonal lineages (A to C, E to Z, and 1 to 4). Of these, lineage I was predominant in the samples so far analyzed. Lineage I also was found in Bangladesh. In plant inoculations onto a set of international and Indian rice cultivars, 38 isolates were screened for pathotype diversity. From the differential disease reactions, 14 pathotypes of Pyricularia grisea were identified and categorized into the international race groups IA, IB, IC, and ID. Data revealed a partial relationship between virulence and phylogeny. Lineages D, E, G, H, J and K formed separate pathotypes and had distinct disease reaction patterns on the differential rice cultivars. However, lineages A, B, C, F, H, I, and J shared more than one pathotype. Forty isolates were inoculated onto seedlings of seven rice isolines (IL-1, IL-6, IL-8, IL10, IL-17 (subset), IL-23, and IL-21) that differ from each other by one or more blast resistance genes. Data on disease reactions on these isolines suggest that the blast resistant gene present in IL-1 could be used to develop a durably blast-resistant rice cultivar for southern India
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