Abstract

Gibberellins (GAs) are labdane-related diterpenoid phytohormones that regulate various aspects of higher plant growth. A biosynthetic intermediate of GAs is ent-kaurene, a tetra-cyclic diterpene that is produced through successive cyclization of geranylgeranyl diphosphate catalyzed by the two distinct monofunctional diterpene synthases—ent-copalyl diphosphate synthase (ent-CPS) and ent-kaurene synthase (KS). Various homologous genes of the two diterpene synthases have been identified in cereals, including rice (Oryza sativa), wheat (Triticum aestivum) and maize (Zea mays), and are believed to have been derived from GA biosynthetic ent-CPS and KS genes through duplication and neofunctionalization. They play roles in specialized metabolism, giving rise to diverse labdane-related diterpenoids for defense because a variety of diterpene synthases generate diverse carbon-skeleton structures. This review mainly describes the diterpene synthase homologs that have been identified and characterized in rice, wheat and maize and shows the evolutionary history of various homologs in rice inferred by comparative genomics studies using wild rice species, such as Oryza rufipogon and Oryza brachyantha. In addition, we introduce labdane-related diterpene synthases in bryophytes and gymnosperms to illuminate the macroscopic evolutionary history of diterpene synthases in the plant kingdom—bifunctional enzymes possessing both CPS and KS activities are present in bryophytes; gymnosperms possess monofunctional CPS and KS responsible for GA biosynthesis and also possess bifunctional diterpene synthases facilitating specialized metabolism for defense.

中文翻译：

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谷物中拉丹烷相关的二萜合酶的演变。

摘要

赤霉素（GAs）是与丹丹有关的二萜类植物激素，可调节植物高生长的各个方面。生物合成的中间气体的是耳鼻喉科-kaurene，即通过由两种不同的单官能二萜synthases-催化香叶基香叶基二磷酸的连续环化制备的四环式二萜ENT -copalyl二磷酸合酶（ENT -CPS）和ENT -kaurene合酶（KS ）。两个二萜合酶的同源性的各种基因在谷物被鉴定，包括稻（稻），小麦（普通小麦）和玉米（玉蜀黍），并且被认为已经从GA生物合成衍生ENT-CPS和KS基因通过复制和新功能化。它们在专门的新陈代谢中发挥作用，由于多种二萜合酶产生各种碳骨架结构，因此产生了多种与拉丹烷有关的二萜类化合物来进行防御。文章主要介绍了已经确定，其特征在于，大米，小麦和玉米，并显示使用野生稻品种，如水稻不同同源通过比较基因组学的研究推断的进化史的二萜合酶同源普通野生稻和短花稻。另外，我们在苔藓植物和裸子植物中引入了与拉丹烷有关的二萜合酶，以阐明植物界中二萜合酶的宏观进化历史。裸子植物具有负责GA生物合成的单功能CPS和KS，还具有促进防御的专门代谢的双功能二萜合酶。