Abstract
Bacillus cereus YN917, obtained from a rice leaf with remarkable antifungal activity against Magnaporthe oryzae, was reported in our previous study. The present study deciphered the possible biocontrol properties. YN917 strain exhibits multiple plant growth-promoting and disease prevention traits, including production of indole-3-acetic acid (IAA), ACC deaminase, siderophores, protease, amylase, cellulase, and β-1,3-glucanase, and harboring mineral phosphate decomposition activity. The effects of the strain YN917 on growth promotion and disease prevention were further evaluated under detached leaf and greenhouse conditions. The results revealed that B. cereus YN917 can promote seed germination and seedling plant growth. The growth status of rice plants was measured from the aspects of rice plumule, radicle lengths, plant height, stem width, root lengths, fresh weights, dry weights, and root activity when YN917 was used as inoculants. YN917 significantly reduced rice blast severity under detached leaf and greenhouse conditions. Genome analysis revealed the presence of gene clusters for biosynthesis of plant promotion and antifungal compounds, such as IAA, tryptophan, siderophores, and phenazine. In summary, YN917 can not only be used as biocontrol agents to minimize the use of chemical substances in rice blast control, but also can be developed as bio-fertilizers to promote the rice plant growth.
Highlights
Rice blast is considered as a devastating disease of rice plants caused by Magnaporthe oryzae (Miah et al, 2017)
Previous studies have reported that Bacillus cereus strains exhibited antifungal activity against M. oryzae in vitro or in vivo, which is expected to be developed as fungicides to control rice blast, such as the B. cereus HS24 (Huang et al, 2020), B. cereus AR156 (Jiang et al, 2020), and B. cereus KF822666 (Hassan et al, 2019)
YN917 showed the maximum 22.54 μg/ml indole-3-acetic acid (IAA) content at the second day of incubation (Figure 2). These results suggest that B. cereus YN917 could produce IAA even in the absence of exogenous tryptophan
Summary
Rice blast is considered as a devastating disease of rice plants caused by Magnaporthe oryzae (Miah et al, 2017). Previous studies have reported that Bacillus cereus strains exhibited antifungal activity against M. oryzae in vitro or in vivo, which is expected to be developed as fungicides to control rice blast, such as the B. cereus HS24 (Huang et al, 2020), B. cereus AR156 (Jiang et al, 2020), and B. cereus KF822666 (Hassan et al, 2019). These studies provided a background for the development of biocides
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