A Biocontrol Strain of Pseudomonas aeruginosa CQ-40 Promote Growth and Control Botrytis cinerea in Tomato

Abstract

Botrytis cinerea infection can be very devastating for tomato production, as it can result in a large-scale reduction in tomato fruit production and fruit quality after harvest. Thus, it negatively affects tomato yield and quality. In this study, a biocontrol bacteria CQ-4 was isolated and screened from the rhizosphere soil of tomato plants. Morphological, physiological, and biochemical characteristics and 16S rDNA sequence analysis revealed that it belongs to the species Pseudomonas aeruginosa, which has a strong antagonistic effect against Botrytis cinerea. In addition, the bacterium’s antibacterial spectrum is relatively extensive, and antagonistic tests have shown that it also has varying degrees of inhibition on other 12 plant diseases. The growth promotion test showed that the strain has a clear promotion effect on tomato seed germination and seedling growth. The growth-promoting effect on plant height, stem thickness, dry and fresh weight and main root length of tomato seedlings was significantly improved after the seeds were soaked in a bacterial solution of 2.5 × 108 cfu mL−1 concentration. This did not only maintain the nutritional quality of tomato fruits, but also prevents them from rotting. In vitro and pot experiments showed that the strain CQ-4 can effectively control tomato gray mold, and the control effects on tomato leaves and fruits reached 74.4% and 66.0%, respectively. Strain CQ-4 induce plants to up-regulate the activities of four disease-resistant defense enzymes. The peak enzymatic activities of Phenylalanine Ammonia Lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), and Superoxide Dismutase (SOD) were increased by 35.6%, 37.6%, 46.1%, and 38.4%, respectively, as compared with the control group. This study found that the strain can solubilize phosphorus, fix nitrogen, and produce cellulase, protease, ferrophilin, and other antibacterial metabolites, but it does not produce chitinase, glucanase, and HCN (hydrocyanic acid). This research screened out an excellent Pseudomonas aeruginosa strain that can stably and effectively control tomato gray mold, and it provided theoretical basis for further development and the application of biological agents.

Streptomyces botrytidirepellens sp. nov., a novel actinomycete with antifungal activity against Botrytis cinerea

“…Pseudomonas aeruginosa CQ-40 had varying degrees of inhibition on B. cinerea and 12 other phytopathogenic fungi. The control effects on tomato leaves and fruits reached 74.4 and 66.0 % [76].…”

“… Pseudomonas aeruginosa CQ-40 had varying degrees of inhibition on B. cinerea and 12 other phytopathogenic fungi. The control effects on tomato leaves and fruits reached 74.4 and 66.0 % [76]. The sterile filtrate of the biocontrol strain Bacillus subtilis WXCDD105 could significantly inhibit mycelial growth of B. cinerea with an inhibition rate of 95.28 %.…”

Postharvest Treatments with Three Yeast Strains and Their Combinations to Control Botrytis cinerea of Snap Beans

“…Snap beans with same size, no disease, and no mechanical damage were selected. The postharvest fruit storage test was conducted after processing as described in Section 2.1, following the method of Wang et al [35] with slight modifications. Single yeast agent, two combined yeast agents, single yeast agent + 0.2% (m/v) NaHCO 3 , single yeast agent + 0.5% (m/v) chitosan, single yeast agent + 1% (m/v) ascorbic acid, and single yeast agent + 0.1% (m/v) konjac powder with a concentration of 10 8 CFU mL −1 and a volume of 3 mL were sprayed evenly on snap beans.…”

“…(1) Mass loss: Mass loss of snap beans was detected by the weighing method with balance instruments. The mass loss of the snap beans was measured from the beginning of storage and measured every 3 days [32,35].…”

“…Mixed the supernatant well, stood for 10 min, and measured the OD value of the supernatant at 290 nm. For the preparation method of reagents R2, R3, R4 and crude enzyme solution, see the kit manual (Nanjing Jiancheng Technology Co., Ltd., Nanjing, China) [35].…”