Population Genetic Structure of Rhizoctonia oryzae-sativae from Rice in Latin America and Its Adaptive Potential to Emerge as a Pathogen on Urochloa Pastures

作者：dos Santos Pereira Danilo A; Ceresini Paulo C; Castroagudin Vanina L; Ramos Molina Lina M; Chavarro Mesa Edisson; Negrisoli Matheus Mereb; Campos Samara Nunes; Pegolo Mauro E S; Takada Helio Minoru

来源：Phytopathology, 2017, 107(1): 121-131.

DOI：10.1094/PHYTO-05-16-0219-R

• aggregated sheath spot
• forage pastures
• reproductive system
• gene flow
• Brachiaria

The fungus Rhizoctonia oryzae-sativae is an important pathogen that causes the aggregated sheath spot disease on rice. In this study, we investigated the genetic structure of rice-adapted populations of R. oryzaesativae sampled from traditional rice-cropping areas from the Paraiba Valley, Sao Paulo, Brazil, and from Meta, in the Colombian Llanos, in South America. We used five microsatellite loci to measure population differentiation and infer the pathogen's reproductive system. Gene flow was detected among the three populations of R. oryzae-sativae from lowland rice in Brazil and Colombia. In contrast, a lack of gene flow was observed between the lowland and the upland rice populations of the pathogen. Evidence of sexual reproduction including low clonality, Hardy-Weinberg equilibrium within loci and gametic equilibrium between loci, indicated the predominance of a mixed reproductive system in all populations. In addition, we assessed the adaptive potential of the Brazilian populations of R. oryzae-sativae to emerge as a pathogen to Urochloa spp. (signalgrass) based on greenhouse aggressiveness assays. The Brazilian populations of R. oryzae-sativae were probably only incipiently adapted as a pathogen to Urochloa spp. Comparison between R-ST and Q(ST) showed the predominance of diversifying selection in the divergence between the two populations of R. oryzaesativae from Brazil.

• 出版日期2017-1