Preliminary Studies On The Interaction Between Ustilaginoidea Virens And Rice

Rice false smut caused by Ustilaginoidea virens (teleomorph:Villosiclava virens) is an important rice fungal disease and distributed in major rice growing area worldwide. It only infects rice spikelets from flowering phase to milk stage. The disease not only affects rice production and quality, but also mycotoxin produced by the causal agent is poisonous to people, domestic animals and birds.This study is based on research pathogenicity differentiation between U. virens and rice varieties, screening different interaction types between U. virens and rice varieties. Then, assay the change of enzyme activity and material content which is related to defense response on compatible/incompatible interaction between U. virens and rice varieties, in order to preliminary clarifythe mechanism of interaction between U. virens and rice varieties. The results of the study are as follows:Firstly, using15strains of U. virens which were come from different geographic origin inoculated10rice varieties respectively to determine pathogenicity of these strains. The results indicate that:(1) Different U. virens strains have different virulence to the same rice variety.(2) Different rice varieties have different resistance to the same U. virens strain.(3) According to the strength of strains’ pathogenicity,15strains can be divided into three categories. First kind is ten weak virulent strains, such as JZ22-2, YH1-2and so on. Second kind is four medium virulent strains. Third kind is one strong virulent strains.(4) According to the resistance of rice varieties to rice false smut,10tested rice varieties can be divided into four categories. First kind is zhenzhunuo, belong to middle resistant level. Second kinds is4rice varieties including IR28and huaidao6, belong to middle susceptible level. Third kinds is4rice varieties including zhuliangyou08and Ⅱyou416, belong to susceptible level. Forth kinds is wanxian98, belong to high susceptible level.Secondly, compare the change of POD, CAT, PAL activity and MDA content which is related to defense response on compatible/incompatible interaction between U. virens and rice varieties. The results indicate that POD and CAT activity on incompatible are stronger than that of compatible interaction. However, PAL activity and MDA content are lower than that of compatible interaction. Finally, compare the expression of OsPR10a, OsPR1a and OsPR1b on compatible and incompatible interaction between U. virens and rice varieties. The results show that the expression of OsPR10a, OsPRla and OsPRlb on incompatible interaction is stronger than those on compatible interaction.