WRKY44 represses expression of the wound-induced sesquiterpene biosynthetic gene ASS1 in Aquilaria sinensis
WRKY44 represses expression of the wound-induced sesquiterpene biosynthetic gene ASS1 in Aquilaria sinensis
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WRKY44 抑制沉香中伤口诱导的倍半萜生物合成基因 ASS1 的表达
DOI：
10.1093/jxb/erz469
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发表时间：
2020-01-23
影响因子：
6.9
通讯作者：
Wei, Jian-He
中科院分区：
文献类型：
--
作者：
Sun, Pei-Wen;Xu, Yan-Hong;Wei, Jian-He
沉香是从沉香树的伤口中提取的，广泛用于传统药物、熏香和香水。倍半萜烯是沉香中的主要活性成分之一，已知是由创伤或伤害引起的；然而，创伤导致倍半萜形成的分子机制仍然很大程度上未知。沉香倍半萜合酶 1 (ASS1) 是负责倍半萜生物合成的关键酶之一，也是一种重要的茉莉酸 (JA) 响应性伤口诱导合酶。然而，目前尚不清楚为什么 ASS1 在健康树木中不表达，以及受伤后如何诱导其表达。在这里，我们报道ASS1是一种伤口诱导基因，其启动子中的242 bp区域（-973至-731 bp）被确定为响应伤口信号的核心序列。 AsWRKY44 直接结合到该区域并抑制 ASS1 启动子活性。 AsWRKY44 的下调或破坏可以解除抑制并激活 ASS1 表达。此外，外源施加茉莉酸甲酯后，AsWRKY44 被降解，ASS1 的表达显着上调。因此，AsWRKY44 是伤口诱导的 ASS1 转录的关键负调节因子，并且是沉香中倍半萜生物合成机制的核心。
Agarwood is derived from wounds in Aquilaria trees and is widely used in traditional medicine, incense, and perfume. Sesquiterpenes are one of the main active components in agarwood and are known to be induced by wounding or injury; However, the molecular mechanisms by which wounding leads to sesquiterpene formation remain largely unknown. Agarwood sesquiterpene synthase 1 (ASS1) is one of key enzymes responsible for the biosynthesis of sesquiterpenes and is a crucial jasmonate (JA)-responsive wound-inducible synthase. However, it is not known why ASS1 is not expressed in healthy trees and how its expression is induced as a result of wounding. Here, we report that ASS1 is a wound-induced gene with a promoter in which a 242-bp region (-973 to -731bp) is identified as the core sequence for responding to wound signals. AsWRKY44 binds directly to this region and represses ASS1 promoter activity. Down-regulation or disruption of AsWRKY44 can relieve the inhibition and activate ASS1 expression. In addition, AsWRKY44 is degraded and the expression of ASS1 is significantly up-regulated in response to exogenous application of methyl jasmonate. Thus, AsWRKY44 is a crucial negative regulator of wound-induced ASS1 transcription, and is central to the mechanism of sesquiterpene biosynthesis in agarwood.