Department of Biology I, Ludwig-Maximilians University of Munich, 82152 Planegg-Martinsried, Germany.
Department of Cellular Biochemistry, University Medical Center Göttingen, 37073 Göttingen, Germany.
Proc Natl Acad Sci U S A. 2019 May 21;116(21):10568-10575. doi: 10.1073/pnas.1900482116. Epub 2019 May 8.
Jasmonates are vital plant hormones that not only act in the stress response to biotic and abiotic influences, such as wounding, pathogen attack, and cold acclimation, but also drive developmental processes in cooperation with other plant hormones. The biogenesis of jasmonates starts in the chloroplast, where several enzymatic steps produce the jasmonate precursor 12-oxophytodienoic acid (OPDA) from α-linolenic acid. OPDA in turn is exported into the cytosol for further conversion into active jasmonates, which subsequently induces the expression of multiple genes in the nucleus. Despite its obvious importance, the export of OPDA across the chloroplast membranes has remained elusive. In this study, we characterized a protein residing in the chloroplast outer membrane, JASSY, which has proven indispensable for the export of OPDA from the chloroplast. We provide evidence that JASSY has channel-like properties and propose that it thereby facilitates OPDA transport. Consequently, a lack of JASSY in leads to a deficiency in accumulation of jasmonic acids, which results in impaired expression of jasmonate target genes on exposure to various stresses. This results in plants that are more susceptible to pathogen attack and also exhibit defects in cold acclimation.
茉莉酸是至关重要的植物激素，不仅在应对生物和非生物胁迫（如创伤、病原体攻击和低温驯化）的应激反应中发挥作用，而且还与其他植物激素一起驱动发育过程。茉莉酸的生物合成始于叶绿体，其中几个酶促步骤从α-亚麻酸产生茉莉酸前体 12-氧代-顺-2-戊烯酸（OPDA）。OPDA 反过来被输出到细胞质中以进一步转化为活性茉莉酸，随后诱导核内多个基因的表达。尽管它的重要性显而易见，但 OPDA 穿过叶绿体膜的输出仍然难以捉摸。在这项研究中，我们鉴定了一种定位于叶绿体外膜的蛋白 JASSY，它对 OPDA 从叶绿体的输出是必不可少的。我们提供的证据表明 JASSY 具有通道样性质，并提出它因此促进了 OPDA 的运输。因此，在 中缺乏 JASSY 会导致茉莉酸积累不足，这会导致暴露于各种胁迫时茉莉酸靶基因的表达受损。这导致植物更容易受到病原体的攻击，并在低温驯化中表现出缺陷。
