Abstract

The plant pathogen Ustilaginoidea virens is known to generate secondary metabolite ustiloxins, which are poisonous to humans and domestic animals and to affect plant cells during the growth process. In this study, rice false smut was collected from different locations in Sichuan province and the strains isolated. The crude toxins of U. virens were extracted from the liquid culture medium of isolated strains to determine the effects on rice seed germination. Our results, as expected, show that the crude toxins had inhibitory effects on the growth of rice germ and radicle. Moreover, these inhibitory effects were maintained even when the toxin was diluted up to 100 times. Crude toxins caused higher inhibition in the radicle than in the germ. Inhibitory effects of crude toxins on rice germination varied significantly depending on the location of where the isolated strains were extracted. This study also showed that inhibition of rice seed germination by crude toxins was different depending on the type of rice used, which corresponded with the field disease resistance evaluation.

Key words: Ustilaginoidea virens, crude toxins, inhibitory effect, significant difference.