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.

中文翻译：

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WRKY44抑制伤口诱导的倍半萜生物合成基因ASS1在中华沉香中的表达。

沉香是从沉香树的伤口中提取的，被广泛用于传统医学，香和香料中。倍半萜是沉香中的主要活性成分之一，已知是由伤或伤害引起的。然而，创伤导致倍半萜形成的分子机制仍然是未知的。沉香倍半萜烯合酶1（ASS1）是负责倍半萜生物合成的关键酶之一，并且是至关重要的茉莉酸酯（JA）响应伤口诱导型合酶。但是，尚不清楚为什么在健康树中不表达ASS1，以及由于受伤如何诱导ASS1的表达。在这里，我们报道ASS1是具有启动子的伤口诱导基因，其中242 bp区域（-973至-731bp）被识别为响应伤口信号的核心序列。AsWRKY44直接与该区域结合并抑制ASS1启动子活性。下调或破坏AsWRKY44可以减轻抑制作用，并激活ASS1表达。此外，AsWRKY44降解，并且响应于茉莉酸甲酯的外源应用，ASS1的表达显着上调。因此，AsWRKY44是伤口诱导的ASS1转录的关键负调控因子，并且是沉香中倍半萜生物合成机制的关键。