Plant J | 诱导型马铃薯 (EE)-法尼醇合酶赋予马铃薯和烟草中细菌病原体的耐受性

今天介绍的是印度科学家在Plant J发表的研究论文《An inducible potato (E,E )-farnesol synthase confers tolerance against bacterial pathogens in potato and tobacco》。

萜烯合酶 (TPS) 在植物中具有多种生物学功能。尽管已经在多个植物物种中报道了TPS在食草动物防御中的作用，但它们在细菌防御中的作用却很少。 

在本研究中，通过功能基因组学，作者报告了马铃薯萜烯合酶 (StTPS18) 在细菌防御中的作用。StTPS18 的表达在叶子中最高，并且响应于丁香假单胞菌和茉莉酸甲酯处理而被诱导。重组StTPS18表现出(EE)-法尼醇合酶活性，利用 (EE)-法尼基二磷酸 (FPP) 形成倍半萜类化合物 (EE)-法尼醇作为唯一产物。  

GFP融合蛋白的亚细胞定位显示StTPS18定位于胞质溶胶。马铃薯中StTPS18 的沉默和过表达分别导致对丁香假单胞菌和青枯菌的耐受性降低和增强。使用含有 (EE)-法尼醇的培养基进行的细菌生长试验显著抑制了丁香假单胞菌的生长。 

此外，过表达转基因马铃薯和普通烟草叶的StTPS18以及渗入马铃薯叶的 (EE)-法尼醇和丁香假单胞菌表现出甾醇途径和发病相关基因成员的表达升高，植物甾醇积累增强。有趣的是，13C3-(EE)-法呢醇渗入马铃薯叶中增强的植物甾醇没有任何明显的13C标记，表明在植物甾醇形成中没有直接利用 (EE)-法呢醇。此外，与对照植物相似，过表达StTPS18的转基因株系的叶子没有可检测到的(EE)-法呢醇，并且释放出比对照更低水平的倍半萜。

这些发现表明StTPS18 及其产物(EE)-法尼醇通过上调植物甾醇生物合成和防御基因间接参与细菌防御。

Terpene synthases (TPSs) have diverse biological functions in plants. Though the roles of TPSs in herbivore defense are well established in many plant species, their role in bacterial defense has been scarce and is emerging. Through functional genomics, here we report the in planta role of potato (Solanum tuberosum) terpene synthase (StTPS18) in bacterial defense. Expression of StTPS18 was highest in leaves and was induced in response to Pseudomonas syringae and methyl jasmonate treatments. The recombinant StTPS18 exhibited bona fide (E,E)-farnesol synthase activity forming a sesquiterpenoid, (E,E)-farnesol as the sole product, utilising (E,E)-farnesyl diphosphate (FPP). Subcellular localization of GFP fusion protein revealed that StTPS18 is localized to the cytosol. Silencing and overexpression of StTPS18 in potato resulted in reduced and enhanced tolerance, respectively, to bacterial pathogens P. syringae and Ralstonia solanacearum. Bacterial growth assay using medium containing (E,E)-farnesol significantly inhibited P. syringae growth. Moreover, StTPS18 overexpressing transgenic potato and Nicotiana tabacum leaves, and (E,E)-farnesol and P. syringae infiltrated potato leaves exhibited elevated expression of sterol pathway and members of pathogenesis-related genes with enhanced phytosterol accumulation. Interestingly, enhanced phytosterols in 13C3-(E,E)-farnesol infiltrated potato leaves were devoid of any noticeable 13C labeling, indicating no direct utilization of (E,E)-farnesol in phytosterols formation. Furthermore, leaves of StTPS18 overexpressing transgenic lines had no detectable (E,E)-farnesol similar to the control plant, and emitted lower levels of sesquiterpenes than the control. These findings point towards an indirect involvement of StTPS18 and its product (E,E)-farnesol in bacterial defense through upregulation of phytosterol biosynthesis and defense genes.

转自：植物生物技术Pbj

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