多粘类芽孢杆菌NSY50增强黄瓜植株枯萎病抗性的呼吸代谢机理研究

Cucumber Fusarium wilt is one of the most destructive soil-borne diseases that threaten cucumber production in protected and field cultivation. To date, biological control has been recognized as a safe, effective and sustainable approach to combat various diseases. In previous study, we isolated a plant-growth-promoting rhizobacteria strain Paenibacillus polymyxa NSY50, which can effectively control cucumber Fusarium wilt, from vinegar residue. Further research found that NSY50 could affect the composition of metabolites under pathogen attack; however, the exact mechanism is not well understood. The purpose of this study is to assess what causes the changes in metabolite compositions. In order to explore the differential response mechanism of respiratory metabolism induced by NSY50, we will explore the positive effects of NSY50 on the activity of key enzymes involved in respiratory metabolism (HK, PK, G-6-PDH and AOX et.), key genes and proteins expression levels after inoculating with the pathogen. Combining resistance phenotypes and inhibitors of G-6-PDH, NADPH oxidase, and AOX, we try to elucidate the mechanism by which NSY50 induced changes in respiratory metabolism enhancing cucumber resistance to Fusarium wilt. The results will provide a theoretical basis for promotion and application of plant growth-promoting rhizobacteria in sustainable agricultural production.

黄瓜枯萎病是一种世界性的土传病害，严重制约着我国设施和大田黄瓜等瓜类作物的栽培生产。生物防治因其安全、高效、对环境无污染等优点日益受到人们关注。前期从醋糟基质中分离得到多粘类芽孢杆菌NSY50，研究发现其可有效防治黄瓜枯萎病，进一步通过代谢物测定观察到代谢组分的差异变化，但其具体作用机制尚不清楚。本研究以主要设施作物黄瓜为试材，采用营养液栽培，研究NSY50对黄瓜植株在枯萎病菌侵害下，根系呼吸代谢途径、能量及呼吸代谢相关酶（如HK、PK、G-6-PDH和AOX等）活性、关键基因及蛋白表达的变化等特征，揭示枯萎病菌侵害下，促生菌NSY50介导的黄瓜根系呼吸代谢差异应答机理；并利用磷酸戊糖途径和交替途径关键酶G-6-PDH、NADPH氧化酶和AOX活性抑制剂，结合抗病表型，阐明促生菌介导的黄瓜根系呼吸代谢变化在增强植株枯萎病抗性的作用机制。为植物根际促生菌在农业生产中的推广和利用提供理论依据。

为研究植物根际促生菌 (PGPR) 在病原体侵害下保护植物的机制，本项目以黄瓜为材料，研究了多粘类芽孢杆菌 NSY50 在增强黄瓜植株枯萎病抗性中的作用和调节作用。主要结果显示：（1）NSY50能够改善黄瓜根系在枯萎病菌侵害下呼吸代谢水平，增强磷酸戊糖途径，降低了脯氨酸、脱氢抗坏血酸、氧化型谷胱甘肽等物质的积累，进而提高黄瓜对枯萎病菌胁迫的耐受性；（2）进一步研究发现，NSY50促进了枯萎病菌侵害下黄瓜根系谷胱甘肽代谢，增强了谷胱甘肽代谢相关酶活性及基因表达，从而维持氧化还原平衡，缓解了病害的发生，而添加谷胱甘肽合成抑制剂丁硫氨酸-亚砜亚胺（BSO），促生菌防病效果减弱；（3）枯萎病菌胁迫下，黄瓜叶片净光合速率、PSⅡ最大光化学效率（Fv/Fm）显著降低，而促生菌NSY50能够提高蔗糖代谢和抗氧化能力，增强光合效率，减缓枯萎病菌对黄瓜幼苗生长的抑制作用。上述结果表明，植物根际促生菌NSY50能够改善黄瓜呼吸代谢、增强谷胱甘肽代谢和蔗糖代谢水平，进而减缓植物细胞氧化伤害，维持氧化还原平衡，缓解枯萎病菌对黄瓜植株的伤害。该研究为植物根际促生菌在农业生产中的推广和利用提供理论依据。