西瓜枯萎病抗感品种根际微生物群落特征差异及其与病害发生的关系

Microbial communities in the rhizosphere of watermelon varieties resistant and susceptible to Fusarium wilt: differences and relationship with disease occurrence

摘要:

【目的】 通过研究不同基因型作物根际微生物群落特征及其与土传病害发生的关系，揭示根际微生物协助植物抵御土壤病原菌入侵的作用机制。【方法】 以西瓜枯萎病感病品种“早佳8424”和抗病品种“西农8号”为研究对象，在连作障碍严重的土壤中进行盆栽试验，探讨了西瓜抗感病品种根际微生物多样性和群落组成差异及其与土传病害发生的关系。【结果】 与感病品种相比，抗病品种发病程度和根际病原尖孢镰刀菌西瓜专化型(Fusarium oxysporum f. sp. niveum, FON)丰度显著下降。抗感病品种根际细菌和真菌α多样性无显著差异，但β多样性分异明显且其群落组成与FON丰度显著相关。差异分析进一步发现抗病品种根际富集了以放线菌门(Actinobacteria)和根瘤菌科(Rhizobiaceae)等为代表的潜在拮抗菌或有益菌。镰刀菌属(Fusarium)也在抗病品种根际显著富集，但主要以未分类的镰刀菌(unclassified Fusarium)和腐皮镰刀菌(Fusarium solani)为主。此外，抗病品种根际微生物共现网络具有较高的复杂性和稳定性，节点平均度比感病品种增加了18.18%，并且网络中节点和边以放线菌门为主。【结论】 西瓜枯萎病抗病品种与感病品种具有显著不同的根际微生物群落组成，抗病品种根际富集的有益菌群和网络互作关系的强化有利于植物抵抗病原菌入侵。本研究通过解析不同基因型作物根际微生物与土传病害发生的关系，为精准调控作物根际微生物结构和功能防治土传病害提供了重要信息和理论依据。

Abstract:

[Objective] We compared the microbial communities in the rhizosphere of plants with different genotypes and explored the relationship between microbial community and soil-borne disease occurrence, aiming to reveal the underlying mechanisms by which rhizosphere microorganisms assist plants in defending against pathogen invasion. [Methods] A pot experiment was conducted with the soil experiencing severe continuous cropping obstacles to compare the microbial communities in the rhizosphere of a susceptible watermelon variety ‘zaojia 8424’ and a resistant variety ‘xinong 8’ to Fusarium wilt. Furthermore, the relationship between microbial community and the occurrence of Fusarium wilt was explored. [Results] The resistant watermelon variety exhibited significantly lower disease index and pathogen (Fusarium oxysporum f. sp. niveum, FON) abundance than the susceptible watermelon variety. Although no significant difference was observed in the bacterial and fungal alpha diversity in the rhizosphere between resistant and susceptible varieties, the microbial beta diversity showcased significant difference between the two varieties. Moreover, both bacterial and fungal community composition was significantly correlated with pathogen abundance. Linear discriminant analysis effect size (LEfSe) further revealed that the resistant watermelon variety enriched more potential antagonistic or plant growth-promoting taxa represented by Actinobacteria and Rhizobiaceae in the rhizosphere. Interestingly, Fusarium was also enriched in the rhizosphere of the resistant variety, mainly composed of unclassified Fusarium and F. solani. Notably, the co-occurrence network of microorganisms in the rhizosphere of the resistant variety exhibited higher complexity and stability than that of the susceptible variety, with an increase of 18.18% in average degree and the nodes and edges dominated by Actinobacteria. [Conclusion] The watermelon varieties resistant and susceptible to Fusarium wilt demonstrate different microbial community composition in the rhizosphere. The enrichment of beneficial microbial taxa and interconnected co-occurrence network of the resistant variety contribute to plant defense against the pathogen invasion. This study disentangles the relationship between rhizosphere microbial community and soil-borne disease occurrence, providing important information and a theoretical basis for preventing and managing soil-borne diseases.