德国马克斯普朗克研究所Ian T. Baldwin、明斯特大学Shuqing Xu等研究人员合作发现，二萜类化合物的可控羟基化作用可实现植物化学防御而无自身毒性。相关论文于2021年1月15日发表于国际学术期刊《科学》。

研究人员发现，沉默野生烟草Nicotiana attenuata中二萜生物合成相关的两个细胞色素P450会导致严重的自毒症状，这是由不可控的羟基化二萜衍生物抑制鞘脂生物合成引起的。此外，二萜的防御功能是通过抑制性主链羟基化产物抑制草食动物的鞘脂生物合成来实现的。因此，通过调节新陈代谢，烟草植物避免了自身毒性并获得了针对草食动物的防御能力。在植物及其食草动物之间发生的这种相互作用可以反映出植物如何解决有毒化学防御的难题。

据介绍，许多植物特有的代谢产物在草食动物防御中起作用，而破坏其生物合成途径中的特定步骤通常会导致自体毒性。然而，其防御和自身毒性的分子机制仍不清楚。 

附：英文原文

Title: Controlled hydroxylations of diterpenoids allow for plant chemical defense without autotoxicity

Author: Jiancai Li, Rayko Halitschke, Dapeng Li, Christian Paetz, Haichao Su, Sven Heiling, Shuqing Xu, Ian T. Baldwin

Issue&Volume: 2021/01/15

Abstract: Many plant specialized metabolites function in herbivore defense, and abrogating particular steps in their biosynthetic pathways frequently causes autotoxicity. However, the molecular mechanisms underlying their defense and autotoxicity remain unclear. Here, we show that silencing two cytochrome P450s involved in diterpene biosynthesis in the wild tobacco Nicotiana attenuata causes severe autotoxicity symptoms that result from the inhibition of sphingolipid biosynthesis by noncontrolled hydroxylated diterpene derivatives. Moreover, the diterpenes’ defensive function is achieved by inhibiting herbivore sphingolipid biosynthesis through postingestive backbone hydroxylation products. Thus, by regulating metabolic modifications, tobacco plants avoid autotoxicity and gain herbivore defense. The postdigestive duet that occurs between plants and their insect herbivores can reflect the plant’s solutions to the “toxic waste dump” problem of using potent chemical defenses.

DOI: 10.1126/science.abe4713

Source: https://science.sciencemag.org/content/371/6526/255