Effects of the rhizosphere microbial community in interspecific intercropping of rice on the resistance against rice blast

【Objective】The objective of this study was to reveal the relationship between rhizosphere soil bacterial community and rice blast resistance under rice interspecies mixed intercropping. This study provided theoretical basis for clarifying the internal mechanism of rice blast control under rice diverse mixed intercropping. 【Method】A traditional rice blast susceptible variety HKN and four modern rice blast resistant varieties SY63, LY838, LY1259 and YG101 were used to conduct mixed intercropping and monoculture. When the rice grew to the yellow maturity stage, the occurrence of rice neck blast was investigated by the five-point sampling method. The diversity and composition changes of soil bacterial communities in the rhizosphere of rice diverse mixed intercropping were analyzed by 16S rDNA sequencing. 【Result】Mixed intercropping treatment could effectively reduce the occurrence of rice blast, and the control effect of HKN（susceptible variety） under different combinations reached 42.14%-73.27%. The results of rice rhizosphere bacterial community diversity showed that mixed intercropping had slight effects on the Alpha diversity of rice rhizosphere bacterial community. The results of principal coordinate analysis showed that except that the rhizosphere bacterial community structure in the HKN‖YG101 combination had no significant change in the rhizosphere bacterial community structure before and after intercroppting（P＞0.05）, and the rhizosphere bacterial community structure of the other main varieties and intercropped varieties showed significant changes before and after intercropping（P＜0.05, the same below）. The dominant bacterial phyla were Actinobacteriota, Chloroflexi, Firmicutes, Proteobacteria and Acidobacteriota. There were 7 genus with high relative abundance in the rhizosphere and significant changes after HKN intercropping, among which relative abundance of Bradyrhizobium was significantly and positively correlated with the incidence and disease index of rice blast, the relative abundance of Marmoricola was significantly and negatively correlated with the incidence and disease index of rice blast. 【Conclusion】Diverse mixed intercropping can greatly change the rice rhizosphere bacterial community structure and reduce the occurrence of rice blast by enriching Marmoricola and increasing the resistance of susceptible varieties to rice blast.