Abstract
Verticillium wilt (VW) caused by Verticillium dahliae is a devastating soil-borne disease that causes severe yield losses in cotton and other major crops worldwide. Here we conducted a high-throughput screening of isolates recovered from 886 plant rhizosphere samples taken from the three main cotton-producing areas of China. Fifteen isolates distributed in different genera of bacteria that showed inhibitory activity against V. dahliae were screened out. Of these, two Pseudomonas strains, P. protegens XY2F4 and P. donghuensis 22G5, showed significant inhibitory action against V. dahliae. Additional comparative genomic analyses and phenotypical assays confirmed that P. protegens XY2F4 and P. donghuensis 22G5 were the strains most efficient at protecting cotton plants against VW due to specific biological control products they produced. Importantly, we identified a significant efficacy of the natural tropolone compound 7-hydroxytropolone (7-HT) against VW. By phenotypical assay using the wild-type 22G5 and its mutant strain in 7-HT production, we revealed that the 7-HT produced by P. donghuensis is the major substance protecting cotton against VW. This study reveals that Pseudomonas specifically has gene clusters that allow the production of effective antipathogenic metabolites that can now be used as new agents in the biocontrol of VW.
Highlights
Cotton verticillium wilt (VW) is a singularly destructive fungal disease caused by Verticillium dahliae, which is regarded as “the cancer of cotton”
High‐throughput screening for isolates with inhibitory action against V. dahliae Bacterial isolates recovered from 886 plant rhizosphere samples taken from the three main cotton-producing areas of China (Additional file 1: Table S1) were
Results indicated that genes related to the siderophore pyoverdine, type II secretion system (T2SS), type VI secretion system (T6SS), extracytoplasmic function (ECF) sigma factors for detecting environmental cues (Kwak et al 2018), phenylacetic acid (PAA) catabolism, acetoin, butanediol catabolism for bacteria-plant communication (Mhlongo et al 2018), and AHLs-mediated quorum-sensing were commonly distributed in the strains we analyzed (Fig. 3e)
Summary
Cotton verticillium wilt (VW) is a singularly destructive fungal disease caused by Verticillium dahliae, which is regarded as “the cancer of cotton”. The V. dahliae fungus invades the vascular system through the roots and soon causes systemic infection, leading to a series of symptoms including leaf chlorosis, necrosis or wilting, leaf or boll abscission, and even plant death. Around 50% of the cotton planting area in China (2.5 million hectares) is VW-infected, leading to direct economic losses of about 250–310 million USD annually (Wang et al 2016). Disease management mainly includes crop rotation to non-host plants, fungicide fumigation and breeding of resistant cultivars (Klosterman et al 2009). Crop rotation is a preventative, but not curative disease management strategy since V. dahliae can survive for
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
