荧光假单胞菌2P24防控瓜类果斑病机制初探

Preliminary Study on The Control Mechanism of Pseudomonas fluorescens 2P24 on Bacterial Fruit Blotch

为初步解析荧光假单胞2P24对瓜类细果斑病的防控机制,测试其次生代谢物2,4-DAPG、MPC对西瓜嗜酸菌Acidovorax citrulli生长的影响,并比较分析2P24及其突变株△phlD(丧失2,4-DAPG合成能力)及△gacS(丧失2,4-DAPG、HCN、蛋白酶合成能力)的病害防控效果和对甜瓜生理生化指标的影响。结果表明,2,4-DAPG及MPC对病原菌的生长、游动性及生物膜的形成均具有抑制作用;与2P24相比,△phlD对病原菌的生长抑制降低,△gacS丧失生长抑制作用。△phlD及△gacS病害相对防治率分别下降了44.3%和77.1%。2P24对于西瓜、甜瓜幼苗有明显的促生作用,可显著提高幼苗株高和鲜重,同时发现2P24可在病原菌接种后诱导甜瓜抗性相关酶SOD、CAT、POD活性提升及3个相关抗性基因MELO3C023441、MELO3C022146及MELO3C004303的表达。本研究结果为瓜类果斑病的生物防治研究提供了参考和理论依据。

In order to explore the mechanism of Pseudomonas fluorescens 2P24 against bacterial fruit blotch,the effects of the secondary metabolites,2,4-DAPG and MPC on the growth of the pathogen,Acidovorax citrulli were tested.The disease control efficacy of 2P24 and its mutantsΔphlD(lack of 2,4-DAPG synthesis)andΔgacS(lack of 2,4-DAPG,HCN and protease synthesis)were compared and analyzed.The results showed that 2,4-DAPG and MPC inhibited the growth,motility,and biofilm formation of A.citrulli.Compared with 2P24,the growth inhibition effect of△phlD decreased andΔgacS lost.The relative control efficacy ofΔphlD andΔgacS reduced by 44.3%and 77.1%,respectively,comparing to 2P24.2P24 promoted the growth of watermelon and melon seedlings,increased the height and fresh weight of seedlings.In addition,2P24 improved the activity of SOD,CAT and POD of melon and increased the expression of three resistance related genes,MELO3C023441,MELO3C022146,MELO3C004303.This study provided a reference and theoretical basis for the biological control of bacterial fruit blotch.