Role of terpene synthases in the defense of Medicago truncatula against Aphanomyces euteiches

植物作为无根生物与多种生物相互作用，包括致病菌，如导致豆科植物根腐病的卵菌。摘要短叶紫花苜蓿的根与植物游动孢子的早期接触导致其萜类合成酶（tps）基因的表达增强。其中，MtTPS10被鉴定为一种多产物倍半萜合成酶，仅与卵菌的游动孢子接触后在根中特异性表达。MtTPS10产物，如主要产物喜马草酚，有助于根对根的抗性，但在植物中被修饰。第一个候选细胞色素P450酶（cypa）转化himachalol已经确定。此外，对不同生态型短尾曲霉的分析表明，MtTPS10的表达水平与对白僵菌的抗性之间往往存在相关性。一个例外是第368行，它对A. euteiches具有高度抗性，但完全缺乏MtTPS10的表达。转录组分析显示，在第368行中表达了先前未被表征的萜烯合成酶（MtTPS-X）。在项目的更新过程中，将检验以下假设：(i) MtTPS-X有助于短尾结核分枝杆菌368系的免疫；（ii） MtTPS10和MtTPS-X的转基因表达增强了马铃薯对疫霉的抗性；（iii） cypa转化植物中的MtTPS10产物。计划利用转基因方法从功能上证明368行MtTPS-X在抗白叶蚜中的作用。此外，MtTPS10和MtTPS-X将在马铃薯植株中组成性表达，并测试其对病原菌的抗性。此外，还将通过突变株的特征分析cypa在植物体内喜马他酚转化中的作用。这些研究有望大大提高我们对tps及其产物在根系防御反应中的作用的认识，不仅对卵菌诱导的根系疾病的潜在控制，而且对卵菌诱导的植物疾病的一般控制都具有重要意义。

Plants as sessile organisms interact with a variety of organisms, including pathogens such as the oomycete Aphanomyces euteiches, which causes root rot in legumes. The early contact of Medicago truncatula roots with zoospores of A. euteiches leads to an enhanced expression of genes encoding terpene synthases (TPSs). Among them, MtTPS10 was identified as a multi-product sesquiterpene synthase specifically expressed in roots and only upon contact with zoospores of oomycetes. MtTPS10 products, such as the major product himachalol, contribute to the resistance of M. truncatula roots to A. euteiches but are modified in planta. First candidate cytochrome P450 enzyme (CYP-A) converting himachalol has been identified. Furthermore, analysis of different ecotypes of M. truncatula showed that there is often a correlation between MtTPS10 expression levels and resistance to A. euteiches. One exception is line 368, which is highly resistant to A. euteiches but completely lacks MtTPS10 expression. Transcriptome profiling revealed the expression of a previously uncharacterized terpene synthase (MtTPS-X) in line 368. In the renewal of the project the following hypotheses will be tested: (i) MtTPS-X contributes to the immunity of M. truncatula line 368; (ii) transgenic expression of MtTPS10 and MtTPS-X increases resistance of potato plants to Phytophthora infestans; and (iii) CYP-A converts MtTPS10 products in planta. It is planned to functionally proof the role of MtTPS-X in line 368 in defense against A. euteiches by transgenic approaches. Furthermore, MtTPS10 and MtTPS-X will be constitutively expressed in potato plants followed by testing their resistance to P. infestans. In addition, the function of CYP-A in the conversion of himachalol in planta will be analyzed by characterization of mutant plants. These studies are expected to greatly enhance our understanding of the role of TPSs and their products in root defense responses and will be important not only for potential control of oomycete-induced root diseases, but for control of oomycete-induced plant diseases in general.