title: Magnaporthe oryzae populations adapted to finger millet and rice exhibit distinctive patterns of genetic diversity, sexuality and host interaction.
abstract: 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.
authors.affiliation: University of Warwick, Coventry, UK.
authors.forename: J P
authors.initials: JP
authors.lastname: Takan
authors.forename: J
authors.initials: J
authors.lastname: Chipili
authors.forename: S
authors.initials: S
authors.lastname: Muthumeenakshi
authors.forename: N J
authors.initials: NJ
authors.lastname: Talbot
authors.forename: E O
authors.initials: EO
authors.lastname: Manyasa
authors.forename: R
authors.initials: R
authors.lastname: Bandyopadhyay
authors.forename: Y
authors.initials: Y
authors.lastname: Sere
authors.forename: S K
authors.initials: SK
authors.lastname: Nutsugah
authors.forename: P
authors.initials: P
authors.lastname: Talhinhas
authors.forename: M
authors.initials: M
authors.lastname: Hossain
authors.forename: A E
authors.initials: AE
authors.lastname: Brown
authors.forename: S
authors.initials: S
authors.lastname: Sreenivasaprasad
mesh_terms: D017954:Africa South of the Sahara; D000351:Africa, Eastern; D054458:Amplified Fragment Length Polymorphism Analysis; D031748:Eleusine / Q000382:microbiology*; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D054884:Host-Pathogen Interactions / Q000235:genetics; D020082:Magnaporthe / Q000235:genetics* / Q000472:pathogenicity*; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*