Guan Pingyin, Schmidt Florian, Fischer Jochen, Riemann Michael, Thines Eckhard, Nick Peter
College of Horticulture, China Agricultural University, Beijing 100193, China.
Institut für Biotechnologie und Wirkstoff-Forschung gGmbH, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany.
Hortic Res. 2022 Aug 1;9:uhac120. doi: 10.1093/hr/uhac120. eCollection 2022.
Grapevine trunk diseases (GTDs) affect grape production and reduce vineyard longevity worldwide. Since the causative fungi also occur in asymptomatic trunks, we address disease outbreak in terms of altered chemical communication between host and endophyte. Here, we identified four chemically similar secondary metabolites secreted by the GTD-associated fungus to analyse their modes of action in a grapevine cell culture of , where microtubules were tagged by GFP. Treatment with the metabolite eutypine activated defence responses, evident from extracellular alkalinisation and induction of defence genes. Eutypinol, instead, eliminated microtubules, in contrast to the other three compounds. Furthermore, we evaluated the effect of four corresponding chemical analogues of these compounds, sharing the phenolic but lacking the alkyne moiety. These analogues were able to induce similar defence responses in cells, albeit at reduced amplitude. Since closely related moieties differing only in details of the side groups at the phenolic ring differ significantly with respect to the response of the host cell, we propose that these fungal compounds act through a specific binding site at the membrane of grapevine cells. We corroborate this specificity by combination experiments, where the eutypine and the eutypinol analogues behave competitively with respect to the elicited responses. In summary, secretes compounds that elicit host defence in a specific manner by interfering with early events of immunity signalling. This supports the notion that a real understanding of GTDs has to address inter-organismic chemical communication.
葡萄树干病害（GTDs）影响全球葡萄生产并缩短葡萄园寿命。由于致病真菌也存在于无症状的树干中，我们从宿主与内生菌之间化学通讯改变的角度来探讨病害爆发问题。在此，我们鉴定了与GTD相关真菌分泌的四种化学结构相似的次生代谢产物，以分析它们在葡萄细胞培养物中的作用模式，其中微管由绿色荧光蛋白（GFP）标记。用代谢产物欧托品处理激活了防御反应，这从细胞外碱化和防御基因的诱导中可以明显看出。相反，与其他三种化合物不同，欧托品醇消除了微管。此外，我们评估了这些化合物的四种相应化学类似物的效果，它们具有酚类结构但缺少炔基部分。这些类似物能够在葡萄细胞中诱导类似的防御反应，尽管幅度较小。由于仅在酚环侧链细节上不同的密切相关部分在宿主细胞反应方面存在显著差异，我们提出这些真菌化合物通过葡萄细胞细胞膜上的特定结合位点起作用。我们通过联合实验证实了这种特异性，在联合实验中，欧托品和欧托品醇类似物在引发的反应方面表现出竞争性。总之，该真菌分泌的化合物通过干扰免疫信号传导的早期事件以特定方式引发宿主防御。这支持了这样一种观点，即真正理解GTDs必须考虑生物体间的化学通讯。
