Abstract

Gibberellins (GAs) play key roles in various developmental processes in land plants. We studied the evolutionary trends of GA metabolic enzymes through a comprehensive homology search and phylogenetic analyses from bryophytes to angiosperms. Our analyses suggest that, in the process of evolution, plants were able to acquire GA metabolic enzymes in a stepwise manner and that the enzymes had rapidly diversified in angiosperms. As a good example of their rapid diversification, we focused on the GA-deactivating enzyme, GA 2-oxidase (GA2ox). Although the establishment of a GA system first occurred in lycophytes, its inactivation system mediated by GA2oxs was established at a much later time: the rise of gymnosperms and the rise of angiosperms through C₁₉-GA2ox and C₂₀-GA2ox development, respectively, as supported by the results of our direct examination of their enzymatic activities in vitro. Based on these comprehensive studies of GA metabolic enzymes, we discuss here that angiosperms rapidly developed a sophisticated system to delicately control the level of active GAs by increasing their copy numbers for their survival under different challenging environments.

中文翻译：

---

陆地植物GA代谢酶的进化

摘要

赤霉素（GAs）在陆地植物的各种发育过程中起着关键作用。我们通过全面的同源搜索和从苔藓植物到被子植物的系统发育分析，研究了GA代谢酶的进化趋势。我们的分析表明，在进化过程中，植物能够逐步获取GA代谢酶，并且这些酶在被子植物中迅速多样化。作为其快速多元化的一个很好的例子，我们集中研究了GA失活酶GA 2-氧化酶（GA2ox）。虽然GA系统的建立首先发生在苔藓植物中，但由GA2oxs介导的灭活系统是在更晚的时间建立的：裸子植物的崛起和通过C ₁₉ -GA2ox和C ₂₀的被子植物的崛起。-GA2ox的发展分别得到我们在体外直接检查其酶活性的结果的支持。基于对GA代谢酶的全面研究，我们在这里讨论被子植物快速发展了一个复杂的系统，通过增加活性GA的拷贝数以在不同的挑战性环境下生存来精确控制活性GA的水平。