Exploration and characterization of low-molecular compound that induces hypersensitive cell death in plants

过敏性细胞死亡(HCD)是植物对病原菌侵染的一种典型的抗病反应。虽然遗传学和生化研究已经确定了许多与HCD的诱导因素有关的因素，但几乎所有这些因素都是蛋白质类因素，很少有人关注与HCD相关的低分子化学物质。我们从烟草花叶病毒(TMV)侵染烟草中分离到一种小分子化合物，该化合物能在30℃的温度下诱导烟草花叶病毒(TMV)引起烟草花叶病毒(HCD)，并通过理化分析鉴定其为二萜顺式松香醇。有趣的是，cis-abienol的化学结构与Waf-1非常相似，waf-1是一种二萜化合物，最初被分离出来作为烟草有丝分裂原激活蛋白激酶(MAPK)WIPK的激活剂，顺-abienol被发现可以诱导细胞死亡相关基因的表达，并激活WIPK和SIPK，另一种烟草MAPK Lb阐明了cisabienol与这些MAPK的关系，我们利用RNAi技术获得了WIPK和SIPK沉默的转基因烟草植株。WIPK/SIPK RNAi植株表现出对HCD的抑制和茉莉酸和水杨酸积累的改变，以响应TMV感染或伤害。顺式松香醇处理WIPK/SIPK RNAi植株可抑制TMV诱导的HCD。这些结果表明顺式松香醇通过激活WIPK和SIPK参与了TMV诱导的HCD。

Hypersensitive cell death (HCD) is a typical disease resistance response of plants against pathogen infection. Although genetical and biochemical studies have identified many factors involved in the induction of HCD, almost all of them are proteineous factors, and little has been focused on low-molecular chemicals responsible for HCD. We isolated a low-molecular compound that can induce HCD in tobacco mosaic virus (TMV)-infected tobacco at 30C, a non-permissive temperature for induction of HCD, and identified it as cis-abienol, a diterpene, by physicochemical analyses. Interestingly, the chemical structure of cis-abienol is very similar to that of WAF-1, a diterpene, which was originally isolated as an activator of the tobacco mitogen-activated protein kinase (MAPK) WIPK, cis-abienol was found to induce expression of cell death-related genes and activation of WIPK and SIPK, another tobacco MAPK lb clarify the relationship between cisabienol and these MAPKs, we generated transgenic tobacco plants in which WIPK and SIPK were silenced using RNAi. WIPK/SIPK RNAi plants exhibited inhibited HCD and altered accumulation of jasmonic and salicylic acids in response to infection with TMV or wounding. Treatment of WIPK/SIPK RNAi plants with cis-abienol compromised TMV-induced HCD. These results suggest that cis-abienol is involved in TMV-induced HCD via activation of WIPK and SIPK.