荧光假单胞菌引发种子对西瓜细菌性果斑病抗性的影响OA

To improve watermelon resistance to bacterial fruit blotch(BFB),Hongdu watermelon seeds were used as test material.Seeds were subjected to bio-priming treatment with Pseudomonas fluorescens 2P24 suspensions at different con-centrations,with sterile water treatment serving as the control(CK).The study investigated the effects of these treatments on seed germination,seedling growth,and resistance to bacterial fruit blotch.The results showed that,compared with CK,the 107 CFU·mL-1 2P24 treatment significantly increased watermelon seed germination rate,germination vigor,germina-tion index,and radicle length.POD and SOD activity in the seeds were significantly higher than those in CK by 113.73%and 87.01%,respectively,and the treatment significantly promoted increases in seedling root length,fresh mass,dry mass,and stem diameter.Following inoculation with the bacterial fruit blotch pathogen Acidovorax citrulli,this treatment helped maintain the stability of photosystem II(PSII)in seedlings and slowed the decline of chlorophyll fluorescence pa-rameters such as Fv/Fm,PI_ABS,φEo,and ψo.Leaf POD,CAT,and SOD activity were significantly increased by 13.65%,76.71%,and 68.34%,respectively,compared to the control,reducing MDA content and significantly lowering the disease severity index.In summary,seed bio-priming with Pseudomonas fluorescens 2P24 at an appropriate concentration can sig-nificantly enhance the resistance of watermelon seedlings to bacterial fruit blotch through multiple pathways,including"promoting germination,promoting growth,protecting PSII,and activating antioxidant defenses".The results of this study provide a theoretical basis and technical reference for the biological control of bacterial fruit blotch in cucurbits.