Pseudomonas bijieensis Strain XL17 within the P. corrugata Subgroup Producing 2,4-Diacetylphloroglucinol and Lipopeptides Controls Bacterial Canker and Gray Mold Pathogens of Kiwifruit

Abstract

Kiwifruit worldwide suffers from the devastating diseases of bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) and gray mold caused by Botrytis cinerea. Here, an endophytic bacterium XL17 isolated from a rape crown gall was screened out for its potent antagonistic activities against Psa and B. cinerea. Strain XL17 and its cell-free culture filtrate (CF) inhibited the growth of Psa and B. cinerea, Psa-associated leaf necrosis, and B. cinerea-associated kiwifruit necrosis. Electron microscopy showed that XL17 CF could damage the cell structures of Psa and B. cinerea. Genome-based taxonomy revealed that strain XL17 belongs to Pseudomonas bijieensis within the P. corrugata subgroup of the P. fluorescens species complex. Among the P. corrugata subgroup containing 31 genomospecies, the presence of the phl operon responsible for the biosynthesis of the phenolic polyketide 2,4-diacetylphloroglucinol (DAPG) and the absence of the lipopeptide/quorum sensing island can serve as the genetic marker for the determination of a plant-protection life style. HPLC detected DAPG in extracts from XL17 CF. MALDI-TOF-MS analysis revealed that strain XL17 produced cyclic lipopeptides of the viscosin family and orfamide family. Together, phenotypic, genomic, and metabolic analyses identified that P. bijieensis XL17 producing DAPG and cyclic lipopeptides can be used to control bacterial canker and gray mold pathogens of kiwifruit.

Paenibacillus polymyxa YLC1: a promising antagonistic strain for biocontrol of Pseudomonas syringae pv. actinidiae, causing kiwifruit bacterial canker

“…7,8 Biocontrol agents have attracted increasing attention owing to their advantages of being environmentally friendly and not easily susceptible to drug resistance. To identify biocontrol agents against kiwifruit canker, Pseudomonas sp., 9 Bacillus sp., 10 Lactobacillus sp., 11 Aureobasidium sp., 12 Streptomyces sp., 13 and others have been studied and shown to inhibit Psa in laboratory tests. Formulations such as Aureo® Gold and BOTRY-Zen®have been used as biological control agents for KBC in New Zealand.…”

Insights into the Biocontrol Function of a Burkholderia gladioli Strain against Botrytis cinerea

“…was active against Penicillium spp. and B. cinerea ( 19 ); 2,4-diacetylphloroglucinol and lipopeptides extracted from Pseudomonas bijieensis were active against bacterial canker and gray mold disease of kiwifruit ( 20 ). Various VOCs such as acetoin, acetic acid, 2,3-butanediol, isopentanol, dimethyl disulfide, and isopentyl isobutanoate released from extremophilic bacteria have effective biocontrol effects against postharvest fungal phytopathogens ( 21 ).…”

Dipicolinic acid enhances kiwifruit resistance to Botrytis cinerea by promoting phenolics accumulation

“…[4][5][6] Botrytis cinerea causes grey mold disease and is the main pathogen affecting preharvest and postharvest kiwifruit. [7][8][9] B. cinerea is a necrotrophic pathogen that penetrates kiwifruit peel via the formation of appressoria and advances through the internal layers of the fruit, producing discoloration and softening. This pathogen secretes oxalic acid, which lowers the pH of the host tissues and stimulates the production of plant-degrading enzymes.…”

“…Botrytis cinerea causes grey mold disease and is the main pathogen affecting preharvest and postharvest kiwifruit 7–9 . B. cinerea is a necrotrophic pathogen that penetrates kiwifruit peel via the formation of appressoria and advances through the internal layers of the fruit, producing discoloration and softening.…”