Characterization of the Sheath Blight Complex of Fungi in Rice (Oryza sativa L.)

RICE sheath blight is the most economically substantial rice disease worldwide that leads to significant grain yield and quality losses. Rhizoctonia solani is the causal agent of sheath blight. However, other fungal species are also associated with sheath blight and could aggravate the disease complex. This study investigated the fungi associated with the sheath blight complex of rice (Oryza sativa L.). Three isolates showed different morphological characteristics in terms of colony color, hyphal size, hyphal branching, and sclerotia formation and size. Identification by Internal Transcribed Spacer (ITS) sequence revealed their identities as R. solani AG1-IA, Chaetomium globosum, and Poitrasia circinans. C. globosum and P. circinans were associated with rice sheath blight. A phylogenetic tree differentiated R. solani AG1-IA from C. globosum and P. circinans and revealed other R. solani AG-4 and AG2-2IIIB subgroups and fungi that could cause the sheath rot of rice (Fusarium proliferatum, F. hainanense, F. sulawesianense, and Sarocladium oryzae).