Abstract

Twelve-oxo-phytodienoic acid (OPDA), the cyclopentenone precursor of jasmonic acid (JA), is required for the wounding response of plants. OPDA is derived from plastid-localized α-linolenic acid (α-LeA; 18:3) via the octadecanoid pathway, and is further exported from plastids to the cytosol for JA biosynthesis. However, the mechanism of OPDA transport from plastids has yet to be elucidated. In the current study, a plastid inner envelope-localized protein, designated 12-oxo-Phtyodienoic Acid Transporter 1 (OPDAT1), was identified and shown to potentially be involved in OPDA export from plastids, in Populus trichocarpa. Torr. OPDAT1 is expressed predominantly in young leaves of P. trichocarpa. Functional expression of OPDAT1 in yeast cells revealed that OPDAT1 is involved in OPDA transport. Loss-of-function of OPDAT1 in poplar resulted in increased accumulation of OPDA in the extracted plastids and a reduction in JA concentration, whereas an OPDAT1-overexpressing line showed a reverse tendency in OPDA accumulation and JA biosynthesis. OPDAT1 transcripts were rapidly induced by mechanical wounding of leaves, and an opdat1 mutant transgenic plant displayed increased susceptibility to spider mite (Tetranychus urticae) infestation. Collectively, these data suggest that OPDAT1 is an inner envelope transporter for OPDA, and this has potential implications for JA biosynthesis in poplar under environmental stresses.

中文翻译：

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OPDAT1，一种质体包膜蛋白，参与杨树茉莉酸生物合成的 12-氧代植物二烯酸输出

摘要

十二氧代植物二烯酸 (OPDA) 是茉莉酸 (JA) 的环戊烯酮前体，是植物损伤反应所必需的。OPDA 来源于质体定位的 α-亚麻酸 (α-LeA; 18:3)，通过十八烷酸途径，并进一步从质体输出到细胞质中用于 JA 生物合成。然而，从质体转运 OPDA 的机制尚未阐明。在当前的研究中，鉴定了一种质体内部包膜定位蛋白，称为 12-氧代-Phtyodienoic Acid Transporter 1 (OPDAT1)，并表明其可能参与毛果杨中质体的 OPDA 输出。托。OPDAT1主要在P. trichocarpa 的幼叶中表达。OPDAT1 的功能表达在酵母细胞中显示 OPDAT1 参与 OPDA 运输。杨树中OPDAT1的功能丧失导致提取的质体中OPDA 的积累增加和 JA 浓度的降低，而OPDAT1过表达的株系在OPDA积累和 JA 生物合成中显示出相反的趋势。OPDAT1转录物被叶子的机械损伤迅速诱导，并且opdat1突变体转基因植物对叶螨（Tetranychus urticae）侵染的易感性增加。总的来说，这些数据表明 OPDAT1 是 OPDA 的内膜转运蛋白，这对环境胁迫下杨树的 JA 生物合成具有潜在意义。