稻瘟病菌拮抗性大豆根瘤内生细菌的筛选及抑制效果

【目的】从河南大豆根瘤的内生细菌资源中筛选对稻瘟病菌有拮抗作用的菌株,初步探讨其抑菌效果,为进一步研究其抑菌机理提供菌种资源。【方法】以稻瘟病菌为供试病原菌,采用对峙法进行拮抗性菌株筛选,显微观察法研究受抑制病原菌菌丝变化,对筛选拮抗性菌株进行细胞形态学及生理生化特性试验、16S rRNA基因测序和系统发育分析及接种防效试验。【结果】经复筛有17株内生菌拮抗效果较明显,最高抑制率为62.16%;受抑制病原菌丝呈现弯曲打结、断裂、原生质浓缩等畸形状态。拮抗性筛选过程中内生菌快速生长形成生物薄膜,包埋菌丝并使其断裂。拮抗菌株分布在7属9种,稻瘟病拮抗性大豆根瘤内生菌呈现种属多样性。防效试验表明内生菌处理组稻苗发病率和病情指数均显著降低,防治效果最高达74.19%。【结论】大豆根瘤内生拮抗性菌株具有种属多样性,拮抗性菌株处理组稻苗发病率和病情指数均显著降低,防治效果显著,为进一步研究其抑菌机理提供菌种资源。

Screening and inhibitory effect of antagonistic endophytic bacteria associated with soybean root nodules against Magnaporthe grisea

Objective] Strains were screened from endophytic resources of soybean root nodules in Henan province against Magnaporthe grisea, and researched its inhibitory effect in order to provide the species resources for further study inhibitory mechanism. Methods] Taking Magnaporthe grisea as tested pathogens, the endophytic bacteria were characterized by antagonistic tests with confront method, the phytopathogen hyphae were analyzed by microscopic observations, the obvious features of antagonistic strains were determinated by cell morphological observation, physical and biochemistry characteristics, 16S rRNA gene sequencing, phylogenic analysis and biological control effect tests. Results] A total of 17 strains have obvious antagonitic effect by secondary screening, the highest inhibition rate reach 62.16%. Results of microscopic analysis on pathogen hyphae showed that hyphae appear bend knot, fracture, protoplasm concentration, deformity and so on. Interestingly, endophytes rapidly grew to form biofilms on plate during antagonitic screening, and embed hyphae and make it break. Combined with the colony characteristics, physical and biochemistry characteristics and phylogenetic analysis, antagonistic strains were distributed in seven genera and nine species, so antagonistic endophytic bacteria against rice blast possessed species diversity. Control effect tests suggested that rice seedlings incidence and disease index of treatment group with endophytes are significantly lower, biological control efficiency reach up to 74.19%. Conclusion] Diverse strains were screened from endophytic resources of soybean root nodules against Magnaporthe grisea, rice seedlings incidence and disease index of treatment group with endophytes are significantly lower, biological control efficiency reach significant, it provided species resources for further study inhibitory mechanism.