Upregulation of the terpenoid pathway and increased ABA content in flax uponFusarium infection leads to activation of the early plant’s response (PR genes, cell wall remodeling, and redox status). Plants have developed a number of defense strategies against the adverse effects of fungi such as Fusarium oxysporum. One such defense is the production of antioxidant secondary metabolites, which fall into two main groups: the phenylpropanoids and the terpenoids. While functions and biosynthesis of phenylpropanoids have been extensively studied, very little is known about the genes controlling the terpenoid synthesis pathway in flax. They can serve as antioxidants, but are also substrates for a plethora of different compounds, including those of regulatory functions, like ABA. ABA’s function during pathogen attack remains obscure and often depends on the specific plant-pathogen interactions. In our study we showed that in flax the non-mevalonate pathway is strongly activated in the early hours of pathogen infection and that there is a redirection of metabolites towards ABA synthesis. The elevated synthesis of ABA correlates with flax resistance to F. oxysporum, thus we suggest ABA to be a positive regulator of the plant’s early response to the infection.

中文翻译：

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尖孢镰刀菌感染激活亚麻中萜类生物合成途径的质体分支，导致 ABA 合成增加

镰刀菌感染后，萜类途径的上调和亚麻中 ABA 含量的增加导致早期植物反应（PR 基因、细胞壁重塑和氧化还原状态）的激活。植物已经开发出许多防御策略来对抗真菌（如尖孢镰刀菌）的不利影响。一种这样的防御是抗氧化次级代谢物的产生，它分为两大类：苯丙烷和萜类。虽然苯丙烷的功能和生物合成已被广泛研究，但对控制亚麻中萜类化合物合成途径的基因知之甚少。它们可以作为抗氧化剂，但也是许多不同化合物的底物，包括那些具有调节功能的化合物，如 ABA。ABA 在病原体攻击期间的功能仍然不清楚，并且通常取决于特定的植物-病原体相互作用。在我们的研究中，我们发现亚麻中的非甲羟戊酸途径在病原体感染的早期被强烈激活，并且代谢物重新转向 ABA 合成。ABA 合成的增加与亚麻对尖孢镰刀菌的抗性相关，因此我们认为 ABA 是植物对感染的早期反应的正调节剂。