Rhizoctonia solani AG1-IA causing leaf blight in Erythrina indica var. picta in Brazil

摘要

Erythrina indica var. picta (L.) B. & M. (Fabaceae), commonly known as brasileirinho, sunshine tree or coral tree, is a rustic ornamental tree widely used in gardens in Brazil. In March of 2014, leaf blight and intense defoliation in E. indica var. picta were observed in Moju, PA, Brazil (Fig. 1A). The spots were characterized by the presence of mycelia on the leaf surface (Fig. 1A). Microscopic examination of the mycelia revealed association with Rhizoctonia spp. The characteristics observed were a distinct right-angle branching pattern, the constriction of hyphae near the point of origin, and multinucleate individual hyphae compartments (1). The fungus was isolated from infected tissues on potato-dextrose-agar (PDA). The anastomosis group (AG) was determined by pairing the isolate with the following tester strains of multinucleate Rhizoctonia solani group: AG1- IA (CMAA 908) AG1-IB (CMAA 909); AG-2-2 IIIB (CMAA 907); AG3 (CMAA 906); AG4 AHI (CMAA 903); AG4 140 (CMAA 904); AG7-H0 (CMAA 901); AG-BI TS-2-4 (CMAA 905) (2). The isolates were obtained from the Culture Collection of Microorganisms of Environmental and Agricultural Importance (CMAA) of the Brazilian Agricultural Research Corporation, located in Jaguariúna, S?o Paulo. The isolate of E. indica var. picta anastomosed with AG1-IA. The genomic DNA of the isolate was extracted (3), and the ITS-5.8S region was amplified by using the pair of primers ITS4B/ITS1F.