PhytoFrontiers (Dec 2021)
Bacillus subtilis GB519 Promotes Rice Growth and Reduces the Damages Caused by Rice Blast Fungus Magnaporthe oryzae
Abstract
Rice blast disease caused by fungus Magnaporthe oryzae (syn. Pyricularia oryzae) is one of the most damaging diseases of rice, reducing plant production worldwide. In the present study, Bacillus subtilis strain GB519 was identified from the rhizosphere based on predicted signatures of 16S ribosomal DNA and gyrA gene and morphological, biochemical, and physiological characteristics. Treated with B. subtilis GB519, rice plants exhibited increased germination rate, vigor index, shoot length, shoot fresh weight, and root fresh weight coupled with more production of indole acetic acid, organic phosphorus, and inorganic phosphorus. In culture, GB519 inhibited growth of the following rice fungal pathogens (in order from most effective to least effective): M. oryzae, Ustilaginoidea virens, Fusarium graminearum, F. moniliforme, F. oxysporum, and Rhizoctonia solani. Three years of studies showed that, when rice was sprayed with GB519, there were significant reductions in rice blast incidence in both the greenhouse and fields: 70.3 and 62.1% in 2017, 69.9 and 71.6% in 2018, and 75.1 and 75.6% in 2019, respectively. Such reductions were correlated with accumulated hydrolytic enzymes, including amylases, proteases, chitinase, and lipases, and the defense enzyme activity of the total antioxidant capacity, catalase, and superoxide dismutase in rice. Field experiments showed that the biocontrol efficacy of GB519 was similar to that of other biological and chemical fungicides. Our results indicate that B. subtilis strain GB519 promoted plant growth and reduced blast disease and suggest that this strain has potential to be used as a biological control agent against rice blast.[Graphic: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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