Inhibitory effect and possible mechanism of a Pseudomonas strain QBA5 against gray mold on tomato leaves and fruits caused by Botrytis cinerea

Abstract

The fungal pathogen Botrytis cinerea causes gray mold disease on various hosts, which results in serious economic losses. Over the past several decades, many kinds of fungicides have been used to successfully control the disease. Meanwhile, the uses of fungicides lead to environmental pollution as well as a potential threat to the human health by the chemical residues in tomato fruit. Also, the gray mold disease is difficult to control with fungicides. Therefore, exploring alternative measures such as biological controls could be the best choice to control the disease and alleviate damages caused by fungicides. In this study, we isolated and identified a novel Pseudomonas strain termed as QBA5 from healthy tomato plant based on the morphological, biochemical characteristics and molecular detection. The antifungal activity assays revealed that, in the presence of QBA5, conidia germination, germ tube elongation and mycelial growth of B. cinerea were significantly inhibited. Most importantly, QBA5 exerted a significant preventive effectiveness against gray mold on tomato fruits and plants. The possible mechanism of QBA5 involved in the inhibition of B. cinerea was investigated. It revealed that the conidia plasma membrane of B. cinerea was severely damaged by QBA5. Further, four different antifungal compounds in the supernatant of QBA5 were separated by preparative high performance liquid chromatography (PHPLC). Overall, the data indicate that there is a considerable potential for QBA5 to reduce the damage caused by gray mold disease on tomato.

Crop Protection against Botrytis cinerea by Rhizhosphere Biological Control Agent Bacillus velezensis XT1

“…Pathogens that cause major economic losses include the necrotrophic fungus Botrytis cinerea. This fungus, which is known to cause gray mold, affects a wide range of host plants and infects over 200 plant species, including important horticultural crops [ 3 , 4 ]. The disease process of B. cinerea is affected by many pathogenicity determinants, such as host cell wall degradation, cell death and host defense avoidance [ 5 , 6 , 7 , 8 , 9 , 10 ].…”

Antifungal Activity of Lipopeptides From Bacillus XT1 CECT 8661 Against Botrytis cinerea

“…Botrytis cinerea [teleomorph: Botryotinia fuckeliana (de Bary) Whetzel] is a necrotrophic fungi known to be the cause of grey mould. These fungi can infect more than 200 plant species, including horticulturally important crops ( Gao et al, 2018 ). Therefore, it has significant economic relevance, causing huge economic losses ( Dean et al, 2012 ).…”

“…Therefore, it has significant economic relevance, causing huge economic losses ( Dean et al, 2012 ). The ability to produce conidiophores that contain conidia gives it the ability to remain quiescent until conditions are favourable enough to produce the infection ( Gao et al, 2018 ). The production of lytic enzymes along with other phytotoxic metabolites induces cell death in plant tissues, mainly affecting those in a state of senescence or with wounds on their surface ( Finiti et al, 2014 ; Gonzalez-Fernandez et al, 2015 ; Yu et al, 2015 ; Yahaya et al, 2016 ).…”

Menadione Sodium Bisulfite-Protected Tomato Leaves against Grey Mould via Antifungal Activity and Enhanced Plant Immunity

“…It needs to be investigated whether MSB was still effective to cope with much higher disease pressure caused by more than 2 × 10 5 conidia/ml of B. cinerea , because much higher disease pressure of B. cinerea can diminish protective effect of MSB on tomato leaf grey mould. More efficient grey mould control by MSB-pretreatment against the lower diseases suggests that reducing inoculum density of B. cinerea by applying other eco-friendly agents such as beneficial microbes and/or plant defence activators, may improve MSB-mediated grey mould control efficacy during tomato production under a protected greenhouse environment ( Elad et al, 1994 ; Gao et al, 2018 ; Sivakumaran et al, 2016 ; Vicedo et al, 2009 ). It also suggested that repetitive pretreatment with MSB at least two times efficiently increased protection efficacy against tomato grey mould without phytotoxic side effect, showing more decreased grey mould lesions by MSBpretreatment.…”

“…Cell-free supernatant of Pseudomonas sp. QBA5 directly disrupted B. cinerea conidia by destroying plasma membrane integrity, and inhibited conidial germination and germ-tube elongation ( Gao et al, 2018 ). In vitro and in planta destructive nature of MSB to B. cinerea conidia as well as conidial stress responses remains elucidated.…”