First report of sheath brown rot of rice in China and characterization of the causal organism by phenotypic tests and Biolog

摘要

A bacterial disease of rice was observed in autumn of 1998-99 in the fields of Jiaxing and Yuhang, Zhejiang Province, China. Oblong to irregular dark green and water-soaked lesions occurred on the sheath, which later became gray-brown or brown surrounded by an effuse dark brown margin. With severe infection, the entire leaf sheath became necrotic and dried out. The panicles withered, Glumes of panicle emerging from the infected sheath exhibited water-soaked lesions that turned light brown. Grains ofinfected panicles were discolored, deformed, or empty. No bacterial ooze was produced from any part of the infected plant. The disease was first discovered in Japan in the 1950s. Since then, it has been reported in Southeast Asia, South America, and Africa, but not previously in China (Tanii et al 1976, Xie 1996). However, an epiphytic bacterium isolated from a weed was identified as Pseudomonas fuscovaginae in central China in 1986 but not from rice (Duan and Fang 1986). We therefore determined the causal organism and compared it with P. fuscovaginae, the causal organism of sheath brown rot of rice, and other related bacteria.