Bacillus velezensis SYL-3 suppresses Alternaria alternata and tobacco mosaic virus infecting Nicotiana tabacum by regulating the phyllosphere microbial community

Abstract

The occurrence of plant diseases is closely associated with the imbalance of plant tissue microecological environment. The regulation of the phyllosphere microbial communities has become a new and alternative approach to the biological control of foliar diseases. In this study, Bacillus velezensis SYL-3 isolated from Luzhou exhibited an effective inhibitory effect against Alternaria alternata and tobacco mosaic virus (TMV). The analysis of phyllosphere microbiome by PacBio sequencing indicated that SYL-3 treatment significantly altered fungal and bacterial communities on the leaves of Nicotiana tabacum plants and reduced the disease index caused by A. alternata and TMV. Specifically, the abundance of P. seudomo, Sphingomonas, Massilia, and Cladosporium in the SYL-3 treatment group increased by 19.00, 9.49, 3.34, and 12.29%, respectively, while the abundances of Pantoea, Enterobacter, Sampaiozyma, and Rachicladosporium were reduced. Moreover, the abundance of beneficial bacteria, such as Pseudomonas and Sphingomonas, was negatively correlated with the disease indexes of A. alternata and TMV. The PICRUSt data also predicted the composition of functional genes, with significant differences being apparent between SYL-3 and the control treatment group. Further functional analysis of the microbiome also showed that SYL-3 may induce host disease resistance by motivating host defense-related pathways. These results collectively indicate that SYL-3 may suppress disease progression caused by A. alternata or TMV by improving the microbial community composition on tobacco leaves.

Responses of the bacterial community of tobacco phyllosphere to summer climate and wildfire disease

“…In previous studies, Firmicutes (represented by Bacillus sp.) and Cyanobacteria were considered beneficial to plant growth and pathogen control ( Priya et al., 2015 ; Han et al., 2016 ; Liu et al., 2022 ), indicating that plant host might have induced the enrichment of these pathogen antagonists in the phyllosphere during T2 to rescue itself from disease invasion.…”

“…Most Pseudomonas species are beneficial for plants, producing phytohormones and siderophores to the inhibit pathogens ( McSpadden et al., 2001 ; Hsu and Micallef, 2017 ) and induce host systemic resistance to improve morphological and biochemical traits of plants at the same time ( Kumar et al., 2021 ). Besides, the abundance of Pseudomonas was negatively correlated with the disease index caused by pathogens Alternaria alternate (leaf spot or blight disease) tobacco mosaic virus (TMV) both in tobacco ( Liu et al., 2022 ) and tomato ( Gupta et al., 2021 ). Likewise, Sphingomonas sp., is a kind of gram-negative, aerobic foliar and phytohormone-producing bacterium capable of protecting plants from foliar diseases caused by Pseudomonas syringae (wildfire disease pathogen) via substrate competition ( Vogel et al., 2012 ) and various pathogenic fungi (e.g., Alternaria and Arthrinium ) ( Enya et al, 2007 ; Vogel et al., 2012 ; Luo et al, 2019 ) and improving plant growth during stress conditions ( Asaf et al., 2020 ).…”

“…Other frequently present keystone taxa includes Sphingomonas and Labrys. These taxa are reported to be dominant in plant phyllosphere and might play important roles in inhibiting plant disease ( Liu et al., 2021 ; Liu et al., 2022 ).…”

“…Dai et al (2022) investigated the spatiotemporal variation of the community tobacco leaves affected by brown spot disease and found that the relative abundance of Pseudomonas, Sphingomonas, and Methylobacterium increased as tobacco leaves aging gradually. Besides, Liu et al (2022) found that the inoculation of Bacillus velezensis SYL-3 could increase the abundance of beneficial bacteria, (Pseudomonas and Sphingomonas), while suppress the pathogens Alternaria alternata and tobacco mosaic virus (TMV).…”

Determination of Dominant Phyllosphere Microbial Community in Rubber Trees with Powdery Mildew

“…Phyllosphere microorganisms are intimately related to plant growth, and even the occurrence of plant diseases (Liu He, et al, 2022). In 1981, the concept of phyllosphere microorganisms was rst proposed by Blackman, who de ned them as microorganisms that inhabit on surface of plant leaves.…”