Journal of Phytopathology (2016) 164, 534-546

Ahmed S.A. Elshakh, Syed Ishtiaq Anjum, Wen Qiu, Abdulwareth A. Almoneafy, Wang Li, Zhang Yang, Zhou-Qi Cui, Bin Li, Guo-Chang Sun and Guan-Lin Xie (2016)
Controlling and defence-related mechanisms of Bacillus strains against bacterial leaf blight of rice
Journal of Phytopathology 164 (7-8), 534-546
Abstract: Bacillus strains are broadly studied for their beneficial role in plant growth and biological control of plant disease and pest; however, little is known about their underlying mechanisms. In this study, we assessed the controlling and defence-related mechanisms of three Bacillus strains including rice seed-associated strain B. subtilis A15, rhizobacterial strains B. amyloliquefaciens D29 and B. methylotrophicus H8, all of which are against bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae. Results indicated that all three strains showed strong biofilm formation ability. The culture filtrates of each strain significantly suppressed the growth and biofilm formation of X. oryzae, while changes in bacterial cell morphology such as cell swell and severe cell wall alterations were observed through the transmission electron microscopy images. PCR analysis revealed that all three strains harbour the antimicrobial-associated genes that are responsible for biosynthesis of bacillomycin, fengycin, iturin and surfactin. Subsequent real-time qPCR analysis revealed the upregulated expression of fenD and srfAA genes in D29 and H8, and fenD and ituC genes in A15 during their in vitro interaction with X. oryzae. It suggests that the antibacterial mechanisms of the three strains may be at least partially associated with their ability to secrete corresponding lipopeptides. Interestingly, the applications of the three strains in greenhouse conditions were found to be effective in controlling the BLB disease, which was achieved through the activation of inducing systemic resistance resulted from the enhanced activities of defence-related enzymes. This is the first report of demonstration of the mode of antibacterial effect of Bacillus strains against X. oryzae. Overall, data from the current study provide valuable information for biological control of BLB disease in rice.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Guanlin Xie

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Xanthomonas oryzae	Rice (Oryza)
Bacillus subtilis (antagonist)	Xanthomonas oryzae	Rice (Oryza)
Bacillus amyloliquefaciens (antagonist)	Xanthomonas oryzae	Rice (Oryza)
Bacillus methylotrophicus (antagonist)	Xanthomonas oryzae	Rice (Oryza)