Phytotoxin of rice aggregate sheath spot pathogen and its biological activities.

Rice aggregate sheath spot disease occurs in many countries and causes serious yield losses. In China, the disease-causing fungus was reported in 1985, and since then, it has rarely been reported in major rice-growing areas after almost 30 years. Compared with , has a significantly different physiological morphology and growth status, although both fungi affect rice leaves in very similar ways. The optimum temperature for the suitable growth of is 31 °C, which is consistent with previous reports. We extracted phytotoxins from and analyzed its biological activity via the detached leaf and radicle inhibition methods. and exhibit differences in terms of pathogenicity and toxin activity, which indicates that these fungi may produce different toxin components. Based on gas chromatography-mass spectrometry data, esters, phenols, and other components were present in the crude toxin extract of . Our research provides a new method for studying the phytotoxins of . However, further studies are needed to elucidate the pathogenic mechanisms responsible for aggregate sheath spot disease in rice.