National Key Laboratory of Rice Biology, Institute of Insect Science, Zhejiang University, Hangzhou 310029, China.
Plant Physiol. 2011 Dec;157(4):1987-99. doi: 10.1104/pp.111.183749. Epub 2011 Oct 7.
The oxylipin pathway is of central importance for plant defensive responses. Yet, the first step of the pathway, the liberation of linolenic acid following induction, is poorly understood. Phospholipases D (PLDs) have been hypothesized to mediate this process, but data from Arabidopsis (Arabidopsis thaliana) regarding the role of PLDs in plant resistance have remained controversial. Here, we cloned two chloroplast-localized PLD genes from rice (Oryza sativa), OsPLDα4 and OsPLDα5, both of which were up-regulated in response to feeding by the rice striped stem borer (SSB) Chilo suppressalis, mechanical wounding, and treatment with jasmonic acid (JA). Antisense expression of OsPLDα4 and -α5 (as-pld), which resulted in a 50% reduction of the expression of the two genes, reduced elicited levels of linolenic acid, JA, green leaf volatiles, and ethylene and attenuated the SSB-induced expression of a mitogen-activated protein kinase (OsMPK3), a lipoxygenase (OsHI-LOX), a hydroperoxide lyase (OsHPL3), as well as a 1-aminocyclopropane-1-carboxylic acid synthase (OsACS2). The impaired oxylipin and ethylene signaling in as-pld plants decreased the levels of herbivore-induced trypsin protease inhibitors and volatiles, improved the performance of SSB and the rice brown planthopper Nilaparvata lugens, and reduced the attractiveness of plants to a larval parasitoid of SSB, Apanteles chilonis. The production of trypsin protease inhibitors in as-pld plants could be partially restored by JA, while the resistance to rice brown planthopper and SSB was restored by green leaf volatile application. Our results show that phospholipases function as important components of herbivore-induced direct and indirect defenses in rice.
类二十烷酸途径对于植物防御反应至关重要。然而，该途径的第一步，即在诱导后释放亚麻酸，还了解甚少。已经假设磷脂酶 D (PLD) 介导这一过程，但来自拟南芥 (Arabidopsis thaliana) 的关于 PLD 在植物抗性中的作用的数据仍然存在争议。在这里，我们从水稻 (Oryza sativa) 中克隆了两个质体定位的 PLD 基因，OsPLDα4 和 OsPLDα5，它们都对水稻二化螟 (Chilo suppressalis) 的取食、机械损伤和茉莉酸 (JA) 处理有反应。OsPLDα4 和 -α5 的反义表达 (as-pld) 导致这两个基因的表达减少 50%，降低了亚麻酸、JA、绿叶挥发物和乙烯的诱导水平，并减弱了 SSB 诱导的丝裂原活化蛋白激酶 (OsMPK3)、脂氧合酶 (OsHI-LOX) 、过氧化物裂解酶 (OsHPL3) 和 1-氨基环丙烷-1-羧酸合酶 (OsACS2) 的表达。as-pld 植株中类二十烷酸和乙烯信号的受损降低了草食性诱导的胰蛋白酶抑制剂和挥发物的水平，改善了 SSB 和褐飞虱 Nilaparvata lugens 的表现，并降低了 SSB 幼虫寄生蜂 Apanteles chilonis 对植物的吸引力。JA 可以部分恢复 as-pld 植株中胰蛋白酶抑制剂的产生，而绿叶挥发物的应用则恢复了对褐飞虱和 SSB 的抗性。我们的结果表明，磷脂酶作为水稻中草食性诱导的直接和间接防御的重要组成部分发挥作用。
