Mixed bacterial fermentation can control the growth and development of Verticillium dahliae

Abstract

Verticillium wilt is a severe disease caused by Verticillium dahliae, which afflicts many crops, particularly cotton in the Xinjiang province of China. Chemical fungicides are harmful to the environment, and biological control agents against the fungal pathogens of plants provide an alternative to chemicals. Biological control agents include antagonistic bacteria or metabolic products. We investigated the inhibitory effects of two plant-growth-promoting rhizobacterial (PGPR) strains, namely Bacillus tequilensis C-9 and Sphingobacterium A1, against V. dahliae in vitro and in the field. We used the mixed fermentation of two bacteria to inhibit V. dahliae. Antimicrobial assays were performed and showed that spore production and germination, and the virulence protein of V. dahliae were reduced after treatment with cell-free mixed fermentation broth. In field studies, there was improvement in the disease severity, along with declined incidence and index after the treatment in the bud and bell stages. To explore the molecular mechanisms of this inhibition, we studied six metabolism-related genes by real-time quantitative polymerase chain reaction (qRT-PCR). The results showed that in response to mixed fermentation broth, some genes related to growth and development were significantly upregulated, explaining the structural changes observed in V. dahliae. Some genes that regulate oxidative stress were also dramatically induced, indicating that mixed bacterial fermentation had a significant impact on V. dahliae. These results support the idea that the cell-free mixed fermentation broth of Bacillus tequilensis C-9 and Sphingobacterium A1, when applied for biocontrols, can inhibit V. dahliae in vitro and in vivo.Abbreviations: ANOVA: analysis of variance; BE: biocontrol efficacy (%); CFU: colony-forming unit; DI: disease incidence rates (DI %); DS: disease status; PDA: potato dextrose agar; PDB: potato dextrose broth (liquid medium); PGPR: plant-growth-promoting rhizobacteria ARTICLE HISTORY

Opportunities and Challenges in Studies of Host-Pathogen Interactions and Management of Verticillium dahliae in Tomatoes

“…Supplementary Materials: The following are available online at http://www.mdpi.com/2223-7747/9/11/1622/s1, Table S1: Disease compatibility of specific combinations of race-specific secreted effectors (Ave1 and V2) on resistant cultivars of tomatoes containing different combinations of the race 1 (Ve1) and race 2 (V2) resistance phenotypes, Table S2: Biocontrol agents (BCAs) and biologicals with biocontrol activity against Verticillium dahliae, Table S3: Some examples of organic amendments (OAs) with suppressiveness against Verticillium dahliae, Table S4: Examples of sources of carbon from recent studies for anaerobic soil disinfestation of soil-borne pathogens including Verticillium dahliae. References [137,140,[153][154][155][156][157][158][159][160][161]163,164,166,167,169,174,175,224, are cited in the supplementary materials. Funding: This research was funded by a USDA-NIFA Specialty Crop Research Initiative (SCRI) under award number 2016-51181-25404.…”

“…In some cases, mixing different BCAs or their extracts among themselves, or with organic amendments, has provided better management of V. dahliae [ 150 , 155 , 156 ], since mixing increases the biological activities of microbes and/or their extracts. Little information is available regarding the use of biologicals to manage V. dahliae, but oils, derivatives, and extracts from medicinally important plants and some algae are being tested, with encouraging results [ 157 , 158 ].…”

“…The following are available online at , Table S1: Disease compatibility of specific combinations of race-specific secreted effectors (Ave1 and V2) on resistant cultivars of tomatoes containing different combinations of the race 1 (Ve1) and race 2 (V2) resistance phenotypes, Table S2: Biocontrol agents (BCAs) and biologicals with biocontrol activity against Verticillium dahliae , Table S3: Some examples of organic amendments (OAs) with suppressiveness against Verticillium dahliae , Table S4: Examples of sources of carbon from recent studies for anaerobic soil disinfestation of soil-borne pathogens including Verticillium dahliae . References [ 137 , 140 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 163 , 164 , 166 , 167 , 169 , 174 , 175 , 224 , 249 , 250 , 251 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 , 267 , 268 , 269 , 270 , 271 , 272 , 273 , 274 , 275 ...…”

Bacillus circulans GN03 Alters the Microbiota, Promotes Cotton Seedling Growth and Disease Resistance, and Increases the Expression of Phytohormone Synthesis and Disease Resistance-Related Genes

“…Accordingly, beneficial PGPB with inhibitory action against V. dahliae are a promising biocontrol agent for the control of cotton Verticillium wilt. To date, some researchers have isolated multiple strains with biocontrol activities against V. dahliae from Bacillus, Enterobacter, Paenibacillus, Pseudomonas, Serratia, and Streptomyces genera (Erdogan and Benlioglu, 2010;Zhang et al, 2018;Cheng et al, 2020;Hasan et al, 2020;Sherzad and Canming, 2020;Tao et al, 2020;Zhang et al, 2020).…”

The Lethal Effect ofBacillus subtilisZ15 Secondary Metabolites onVerticillium dahliae

“…1 In China, more than 40% of the cotton-growing area is threatened by Verticillium wilt, 2 particularly cotton in the Xinjiang province of China. 3 Verticillium wilt in cotton, caused by the soil-inhabiting fungus Verticillium dahliae Kleb., 1 is difficult to control, due to the formation of microsclerotia, which exist in the soil for a long time. 4 Cultural practices, use of resistant varieties, and application of chemical fungicides are the most common strategies used to control Verticillium wilt of cotton.…”