Gibberellin (GA) is an important hormone, which is involved in regulating various growth and development. GA biosynthesis pathway and synthetase have been basically clarified. Gibberellin 3β hydroxylase (GA3ox) is the key enzyme for the synthesis of various active GA. There are two GA3ox genes (OsGA3ox1 and OsGA3ox2) in rice, and their physiological functions have been preliminarily studied. However, it is not clear how they work together to synthesize active GA to regulate rice development. In this study, the knockout mutants ga3ox1 and ga3ox2 were obtained by CRISPR/Cas9 technology. The pollen fertility of ga3ox1 decreased significantly, while the plant height of ga3ox2 decreased significantly. It shows that OsGA3ox1 is necessary for normal pollen development, while OsGA3ox2 is necessary for stem and leaf elongation. Tissue expression analysis showed that OsGA3ox1 was mainly expressed in unopened flowers, while OsGA3ox2 was mainly expressed in unexpanded leaves. The GA in different tissues of wild type (WT), and two ga3ox mutants were detected. It was found that pollen fertility is most closely related to the content of GA7, and plant height is most closely related to the content of GA1. It was found that OsGA3ox1 catalyzes GA9 to GA7 in flowers, which is closely related to pollen fertility; OsGA3ox2 catalyzes the GA20 to GA1 in unexpanded leaves, thereby regulating plant height; OsGA3ox1 catalyzes the GA19 to GA20 in roots, regulating the generation of GA3. OsGA3ox1 and OsGA3ox2 respond to developmental and environmental signals, and cooperate to synthesize endogenous GA in different tissues to regulate rice development. This study provides a reference for clarifying its role in GA biosynthesis pathway and further understanding the function of OsGA3ox.
赤霉素(gibberellin，GA)是一种重要的激素，参与调控植物多种生长发育过程。GA生物合成通路已基本阐明，其中赤霉素3β羟化酶(gibberellin 3β-hydroxylase，GA3ox)是多种活性GA合成的关键酶。水稻中有2个GA3ox基因(OsGA3ox1和OsGA3ox2)，其生理功能虽有初步研究，但它们在合成活性GA调控水稻发育过程中是如何分工协作尚不清楚。本研究通过CRISPR/Cas9技术获得基因编辑突变体ga3ox1和ga3ox2，发现ga3ox1花粉育性显著下降，而ga3ox2株高显著变矮，表明OsGA3ox1是花粉正常发育必需的，而OsGA3ox2是茎叶伸长必需的。组织表达分析表明，OsGA3ox1主要在未开的花中表达，OsGA3ox2主要在未伸长的叶中表达。进一步对野生型(WT)和两个ga3ox突变体未开的花、未伸长的叶及根中的GA进行检测分析，发现OsGA3ox1在花中催化GA9形成GA7与花粉育性密切相关；OsGA3ox2在未伸长的叶中催化GA20形成GA1调控株高；OsGA3ox1在根中催化GA19形成GA20，调控GA3的生成。总之，OsGA3ox1和OsGA3ox2响应发育信号，在不同组织分工协作合成内源GA，调控水稻生长和发育。本研究为阐明OsGA3ox1和OsGA3ox2在GA生物合成中的作用以及深入理解OsGA3ox的功能提供参考。.
Keywords: