细菌-真菌互作广泛存在于自然界中。先前已有许多关于植物病原细菌与病原真菌互作的研究，但对梨树病原细菌与病原真菌的互作研究却鲜有报道。

南京农业大学胡白石团队在新疆库尔勒香梨园内发现梨腐烂病发生严重的梨园内常伴随梨火疫病的出现。然而这两种病原物在侵染梨树期间的关系尚不清楚。近期，该团队解答了梨火疫病菌（Erwinia amylovora）与梨腐烂病菌（Cytospora pyri）之间是否存在互作以及探究其潜在的协同致病机制，以题为“Cytospora pyri promotes Erwinia amylovora virulence by providing metabolites and hyphae”在Journal of Integrative Agriculture (《农业科学学报》(英文)，JIA) 2024年9期以封面文章正式发表。

胡白石团队首先对采集到的梨树样品进行病原物检测，计算两种病原物的田间共存率；随后对E. amylovora和C. pyri进行了室内离体接种，观测病害的发生情况；最后通过对生长、物理互作、毒力因子产生及毒力因子编码基因表达的监测，解析E. amylovora与C. pyri互作的分子机制。结果表明，E. amylovora与C. pyri可在同一病斑中共存，且在离体梨树组织上同时接种两种病原菌可加重病害的发生。同时发现，C. pyri虽不影响E. amylovora的生长，却可以促进E. amylovora的扩散及毒力因子梨火疫毒素的产生。本研究结果表明，E. amylovora与C. pyri在侵染梨树期间存在协同致病作用，C. pyri可通过菌丝和代谢产物促进E. amylovora的扩散并提高致病力，从而加重病害的发生。

Fig. 2 Virulence assays on pear plants. A and B, virulence assays on pear leaves inoculated with either Erwinia amylovora (Liawt05), Cytospora pyri or a combination of both. C and D, virulence assays of E. amylovora (Liawt05) and C. pyri or a combination of both on pear shoots. E and F, virulence assays of E. amylovora (Liawt05) and C. pyri or a combination of both on annual branches of pears. Lesion length was measured on pear tissues at 7 days post-inoculation (dpi). All the experiments were repeated three times with three replicates per sample and data presented are the mean±SD (ANOVA; * , P<0.05; **, P<0.01).

Fig. 3 Microscopic observation. For microscope observations, Erwinia amylovora was tagged with red fluorescent protein (RFP). Pear shoots and annual branches were inoculated with either E. amylovora (Liawt05), Cytospora pyri or a combination of both. Microscopy pictures of diseased pear tissues was observed with stereo fluorescence microscope.

Fig. 4 Effect of metabolites on bacterial and fungal growth. A, disk diffusion between Erwinia amylovora (Liawt05) and Cytospora pyri. NC indicates the negative control of sterile water. B, growth curves of E. amylovora (Liawt05) in PDB media. C, growth curves of C. pyri in PDB media. All the experiments were repeated three times with three replicates per sample and data presented are the mean±SD.

本文是对梨树病原物E. amylovora与C. pyri互作研究的首次报道，开展梨树病原细菌与病原真菌的协同致病研究，对明确病原物的侵染机制，保证新疆梨产业平稳健康发展具有重要意义。

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‍https://www.sciencedirect.com/science/article/pii/S2095311924002119‍

Cite the article:Tong Shen, Mengdi Ye, Yeping Xu, Bohan Ding, Hongtao Li, Li Zhang, Jun Wang, Yanli Tian, Baishi Hu, Youfu Zhao. 2024. Cytospora pyri promotes Erwinia amylovora virulence by providing metabolites and hyphae. Journal of Integrative Agriculture, 23(9): 3045-3054.

Journal of Integrative Agriculture (《农业科学学报》(英文), JIA) 由中华人民共和国农业农村部主管，中国农业科学院与中国农学会主办，中国农业科学院农业信息研究所承办。综合性英文学术期刊，月刊。创刊于2002年，现任主编为中国科学院院士陈化兰。JIA主要栏目有作物科学、园艺、植物保护、动物科学、动物医学、农业生态环境、食品科学、农业经济与管理等。刊稿类型有综述、研究论文、简报以及评述等。全部论文在Elsevier-ScienceDirect (SD) 平台OA出版。最新SCI影响因子4.6，位于SCI-JCR农业综合学科Q1区。中国科学院分区农林科学1区。2016年以来先后获得中国科协等部委 “提升计划”“登峰计划”“卓越计划”项目支持。