Magnaporthe oryzae Populations Adapted to Finger Millet and Rice Exhibit Distinctive Patterns of Genetic Diversity, Sexuality and Host Interaction

• DOI: 10.1007/s12033-011-9429-z
• Publication Date: 2011-06-23T10:53:14Z
• Authors: J. P. Takan; J. Chipili; S. Muthumeenakshi; N. J. Talbot; E. O. Manyasa; R. Bandyopadhyay; Y. Sere; S. K. Nutsugah; P. Talhinhas; M. Hossain; A. E. Brown; S. Sreenivasaprasad
• Keywords: 570; pathogen populations; magnaporthe oryzae; Eleusine; finger millet; 03 medical and health sciences; pathogenicity; molecular biology; biochemistry; Amplified Fragment Length Polymorphism Analysis; Millets; Africa South of the Sahara; Plant Diseases; 2. Zero hunger; mating type distribution; adaptive divergence; 0303 health sciences; bioengineering; rice; Genetic Variation; Oryza; Magnaporthe oryzae; genetic diversity; Africa, Eastern; blast disease; Magnaporthe; Haplotypes; fertility status; genetic variation; Host-Pathogen Interactions; biotechnology

In this study, host-specific forms of the blast pathogen Magnaporthe oryzae in sub-Saharan Africa (SSA) were characterised from distinct cropping locations using a combination of molecular and biological assays. Finger millet blast populations in East Africa revealed a continuous genetic variation pattern and lack of clonal lineages, with a wide range of haplotypes. M. oryzae populations lacked the grasshopper (grh) element (96%) and appeared distinct to those in Asia. An overall near equal distribution (47-53%) of the mating types MAT1-1 and MAT1-2, high fertility status (84-89%) and the dominance of hermaphrodites (64%) suggest a strong sexual reproductive potential. Differences in pathogen aggressiveness and lack of cultivar incompatibility suggest the importance of quantitative resistance. Rice blast populations in West Africa showed a typical lineage-based structure. Among the nine lineages identified, three comprised ~90% of the isolates. Skewed distribution of the mating types MAT1-1 (29%) and MAT1-2 (71%) was accompanied by low fertility. Clear differences in cultivar compatibility within and between lineages suggest R gene-mediated interactions. Distinctive patterns of genetic diversity, sexual reproductive potential and pathogenicity suggest adaptive divergence of host-specific forms of M. oryzae populations linked to crop domestication and agricultural intensification.