沉默大豆GmATG5加速叶片衰老并增强大豆抗病性

Silencing GmATG5 genes accelerated senescence and enhanced disease resistance in soybean

摘要:

自噬在生物体细胞内物质循环利用及适应各种胁迫方面起着重要作用。然而，对大豆自噬途径的研究鲜有报道。本研究利用大豆豆荚斑驳病毒(bean pod mottle virus, BPMV)介导的基因沉默技术，对大豆自噬相关基因5 (autophagy-related gene 5, ATG5)同源基因进行沉默。结果发现，经暗处理的GmATG5沉默植株叶片上积累过量的ATG8蛋白，说明自噬降解途径受损；与自噬途径受损相一致，暗处理的GmATG5沉默植株叶片出现明显的衰老加速的表型；另外，GmATG5沉默植株叶片中活性氧(reactive oxygen species, ROS)的积累量以及水杨酸含量显著增加，说明沉默GmATG5激活了免疫反应；抗病性分析表明，GmATG5沉默植株对大豆斑点病菌(Pseudomonas syringae pv. glycinea, Psg)的抗性较空载体对照植株显著增强，但该抗病性的增强并不依赖于丝裂原活化蛋白激酶(mitogen-activated protein kinase, MAPK)途径的激活。

Abstract:

Autophagy plays an essential role in recycling/re-utilizing nutrients and in adaptions to numerous stresses. However, the roles of autophagy in soybean have not been investigated extensively. In this study, a virus-induced gene silencing approach mediated by bean pod mottle virus (BPMV) was used to silence autophagy-related gene 5 (ATG5) genes in soybean (referred to as GmATG5). Our results showed that ATG8 proteins were massively accumulated in the dark-treated leaves of the GmATG5-silenced plants relative to the vector control plants (BPMV-0), indicating that autophagy pathway is impaired in the GmATG5-silenced plants. Consistent with the impaired autophagy, an accelerated senescence phenotype was observed on the leaves of the dark-treated GmATG5-silenced plants, which was not shown on the leaves of the dark-treated BPMV-0 plants. In addition, the accumulation levels of both reactive oxygen species (ROS) and salicylic acid (SA) were significantly induced in the GmATG5-silenced plants compared with that of the vector control plants (BPMV-0), indicating an activated immunity. Accordingly, the GmATG5-silenced plants exhibited significantly enhanced resistance against Pseudomonas syringae pv. glycinea (Psg) in comparison with the BPMV-0 plants. Nevertheless, the activated immunity observed in the GmATG5-silenced plant was independent of the activation of mitogen-activated protein kinase (MAPK).