The isolation of the antagonistic strain Bacillus australimaris CQ07 and the exploration of the pathogenic inhibition mechanism of Magnaporthe oryzae.

Wenqian Chen,Hong Xu,Yilun Dong,Songhao Rong,Lu Zhao,Zhengjun Xu,Hui Li,Ying Guan,Lihua Li,Xiaoling Gao,Rongjun Chen,Zonghua Wang

doi:10.1371/journal.pone.0220410

Abstract

Biological control as a promising method to combat plant disease has gained public attention in recent years. In the present study, we isolated 12 strains resistant to Magnaporthe oryzae from western Sichuan subalpine soil. Among them, CQ07 exhibited remarkable activity against M. oryzae. The result of 16S rRNA sequence analysis revealed that CQ07 is approximately 99% similar to Bacillus australimaris. The sterilized culture filtrate of CQ07 inhibited the growth of M. oryzae, which motivated us to deduce the influence of CQ07 on the pathogenicity of M. oryzae. As shown by experimentation, sterilized culture filtrate (10 μl/ml) of CQ07 can delay and even suppress the germination of conidia and prevent the formation of appressorium in vitro and in vivo. In addition, by simulative field tests, the spraying of conidia suspension diluted with sterilized culture filtrate of CQ07 reduced infection of rice blast. To better control rice blasts, understanding the infection mechanism of M. oryzae and inhibiting the mechanism of the antagonistic strain is of great importance.

Highlights

Rice blast caused by the filamentous ascomycete Magnaporthe oryzae is one of the most destructive diseases of rice around the world[1]
16S rRNA sequence analysis indicated that strain CQ07 displayed approximately 99% similarity to Bacillus australimaris
The morphological and physiological characteristics of CQ07 are summarized in Fig 3 and Table 1

Summary

Introduction

Rice blast caused by the filamentous ascomycete Magnaporthe oryzae is one of the most destructive diseases of rice around the world[1]. Outbreaks of rice blast disease are a serious and recurrent problem in China and other rice-growing regions[2]. Many people use antifungal drugs and plant disease-resistant cultivars to reduce the loss caused by rice blasts. Chemical antifungal drugs have many advantages, such as high efficiency and inexpensive use. The overuse of chemical fungicides pollutes the environment and makes pathogenic fungi increasingly drug resistant. The introduction of resistant cultivars can prevent disease efficiently, new variations may lead to the appearance of new pathogenic bacteria[3]

Methods

Results

Conclusion