Morphological and phylogenetic investigation of Bipolaris oryzae and some species of Bipolaris obtained from rice and grass weeds.
Brown spot disease is an important disease of rice in the world and Iran. A collection of 348 Bipolaris isolates was made from cultivated rice paddies and weeds in Mazandaran, Guilan, Golestan, Khuzistan and Fars provinces, during 2011 and 2012. Six species of Bipolaris viz. B. oryzae, B. cynodontis, B. spicifera, B. bicolor, B. sorokiniana and B. neergaardii were identified using morphological and molecular data. Bipolaris oryzae was known as dominant species and the causal agent of rice brown disease in Iran. Based on morphological characteristics, B. oryzae isolates were grouped into four different morphological groups. Maize, muse, Echinochloa colona, Paspalum scrobiculatum and an unknown grass are introduced new hosts for B. oryzae in Iran. Moreover, phylogenetic relationships of some Bipolaris species based on sequencing of rDNA-ITS region and gpd gene have been studied.