Antagonism against crop pathogenic fungi and rice growth-promoting potential of endophytic bacteria Fse32 from Dongxiang wild rice (Oryza rufipogon Griff.)

Abstract:

[Background] Plant seeds are important raw source for screening endophytic bacteria, from which the strains with great application values can be isolated. [Objective] To explore excellent endophyte resources from seeds, we identified the endophytic bacterial strain Fse32 isolated from the seeds of Dongxiang wild rice (Oryza rufipogon Griff.) and evaluated its resistance to pathogenic fungi and growth-promoting effects. [Methods] The isolated bacteria was identified based on morphological, physiological, and biochemical characteristics and 16S rRNA gene sequence. The antagonistic experiment was carried out to determine the inhibitory activities on pathogenic fungi. The tests of growth promoting ability, rice seed germination and pot experiments were conducted to evaluate the growth-promoting effect of the strain. [Results] Endophytic bacteria Fse32 was identified as Burkholderia gladioli Fse32. The strain exhibited remarkable effectiveness against Fusarium graminearum, Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotinia libertiana, Fusarium oxysporum, and Phytophthora capsici. Furthermore, Fse32 displayed excellen growth-promoting potential, the production of Indoleacetic acid (indole-3-acetic acid, IAA) at a yield of 17.95 mg/L, the capability of producing siderophores, with an A/A_r ratio of 0.24 and the inorganic phosphorus-solubilizing ability of 339.07 mg/L. The results of seed germination and pot experiments showed that strain Fse32 significantly promoted rice seed germination, and increased the plant height, root length, dry weight, and total chlorophyll content of rice seedlings by 7.9%, 33.5%, 108.9%, and 68.9% respectively. [Conclusion] Burkholderia gladioli Fse32 is an endophytic bacterium with diverse functions and high efficiency, demonstrating a promising prospect for biocontrol and growth promotion.