Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Fritz-Haber-Weg, Building, Karlsruhe, Germany.
Joint research unit for grapevine health and wine quality (SVQV), INRA, Université de Strasbourg, Colmar, France.
J Exp Bot. 2018 May 25;69(12):2883-2896. doi: 10.1093/jxb/ery133.
Fatty acid hydroperoxides can generate short-chained volatile aldehydes that may participate in plant defence. A grapevine hydroperoxide lyase (VvHPL1) clustering to the CYP74B class was functionally characterized with respect to a role in defence. In grapevine leaves, transcripts of this gene accumulated rapidly to high abundance in response to wounding. Cellular functions of VvHPL1 were investigated upon heterologous expression in tobacco BY-2 cells. A C-terminal green fluorescent protein (GFP) fusion of VvHPL1 was located in plastids. The overexpression lines were found to respond to salinity stress or the bacterial elicitor harpin by increasing cell death. This signal-dependent mortality response was mitigated either by addition of exogenous jasmonic acid or by treatment with diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases. By feeding different substrates to recombinantly expressed enzyme, VvHPL1 could also be functionally classified as true 13-HPL. The cognate products generated by this 13-HPL were cis-3-hexenal and trans-2-hexenal. Using a GFP-tagged actin marker line, one of these isomeric products, cis-3-hexenal, was found specifically to elicit a rapid disintegration of actin filaments. This response was not only observed in the heterologous system (tobacco BY-2), but also in a grapevine cell strain expressing this marker, as well as in leaf discs from an actin marker grape used as a homologous system. These results are discussed in the context of a role for VvHPL1 in a lipoxygenase-dependent signalling pathway triggering cell death-related defence that bifurcates from jasmonate-dependent basal immunity.
脂肪酸氢过氧化物可以生成短链挥发性醛，这些醛可能参与植物防御。葡萄过氧化氢裂合酶 (VvHPL1) 聚类到 CYP74B 类，其功能特征与防御有关。在葡萄叶片中，该基因的转录物在受到创伤后迅速大量积累。通过在烟草 BY-2 细胞中异源表达，研究了 VvHPL1 的细胞功能。VvHPL1 的 C 端绿色荧光蛋白 (GFP) 融合蛋白定位于质体中。发现过表达系通过增加细胞死亡对盐胁迫或细菌激发子 harpin 作出反应。这种依赖于信号的死亡率反应可以通过添加外源茉莉酸或用二苯并碘(DPI)处理来减轻，DPI 是 NADPH 氧化酶的抑制剂。通过向重组表达的酶中添加不同的底物，VvHPL1 也可以被功能分类为真正的 13-HPL。该 13-HPL 产生的同源产物为顺式-3-己烯醛和反式-2-己烯醛。使用 GFP 标记的肌动蛋白标记线，发现这些立体异构体产物中的一种，顺式-3-己烯醛，特异性地引发肌动蛋白丝的快速解体。这种反应不仅在异源系统（烟草 BY-2）中观察到，而且在表达该标记的葡萄细胞系以及用作同源系统的带有肌动蛋白标记的葡萄叶盘中也观察到。这些结果在 VvHPL1 在脂氧合酶依赖性信号通路中发挥作用的背景下进行了讨论，该信号通路触发与茉莉酸盐依赖性基础免疫分叉的细胞死亡相关防御。
