Isolation and Identification of Endophytic Bacteria Inhibiting Phytophthora parasitica var. nicotianae and Promoting Tobacco Seedling Growth

Purpose For tobacco black shank control purpose.

Method The dilution plate and dual culture were proceeded to screen the tobacco seed endophytes activity against Phytophthora parasitica var. nicotiamae. The antagonistic and growth-promotion effects on tobacco seedlings were determined using disc filtrate assay, germination test, greenhouse experiment and floating seedling test.

Result A total of 34 endophytic bacteria were isolated and 4 antagonistic strains with strong inhibitory effect on P. nicotianae. Among them, YN201716 displayed maximum inhibitory zone, and YN201728 had the maximum inhibitory spectrum. The control effect of YN201728 on tobacco black shank reached 58.84% under the greenhouse condition. Moreover, this strain showed a promotion effect on the seed germination and tobacco seedling growth. In addition, the root length, plant height, chlorophyll content, maximum leaf length, leaf width, fresh weight and dry weight of seedlings increase 23.4%, 83.3%, 176.4%, 124.6%, 97.10%, 487.8% and 196.8%, respectively. Based on 16S rRNA sequence alignment, YN201709 and YN201728 strains were identified as Bacillus amyloliquefaciens, YN201702 as B. safensis, and YN201716 as Brevibacillus brevis.

Conclusion The seed-borne endophyte YN201728 displayed good antagonistic and growth-promoting effect on tobacco, and has great potential for development as microbial pesticide and bacterial fertilizer.