AtGH3.17调控拟南芥生长素和油菜素甾醇的响应

植物激素油菜素甾醇和生长素在植物生长发育过程中发挥重要作用, 且两者之间存在复杂的调控关系。为探究拟南芥(Arabidopsis thaliana)生长素早期响应基因GH3.17是否参与生长素和油菜素甾醇之间的调控, 利用转基因技术和CRISPR/Cas9基因编辑系统分别获得拟南芥GH3.17过表达和缺失突变植株, 并对其表型进行比较分析。结果显示, 与野生型相比, GH3.17缺失突变体的根长增加, 而GH3.17过表达植株呈现根长变短、叶片卷曲、叶柄缩短和株高变矮等典型的生长素缺陷表型。采用一定浓度的生长素或者油菜素甾醇处理植株, 结果显示过表达植株的根明显变长, 表明其对生长素以及油菜素甾醇的响应更为敏感。通过qRT-PCR分析过表达植株中生长素信号通路和油菜素甾醇合成通路相关基因的表达情况, 发现生长素信号通路基因Aux/IAA家族成员IAA12和IAA16的表达受到抑制, 而油菜素甾醇合成酶基因DWF4和CPD的表达量增高。综上, 推测活性生长素含量减少导致的生长素信号被抑制可以通过增加油菜素甾醇合成来进行一定的补偿。

Brassinosteroid and auxin play important roles in plant growth and development. There is a complex crosstalk between the two plant hormones. In order to study whether GH3.17 is involved in the crosstalk between auxin and brassinosteroid (BR), we created overexpression and CRISPR gene loss mutants of Arabidopsis GH3.17. The root length of GH3.17 CRISPR mutants was slightly longer than that of wild-type plants. However, the GH3.17 overexpression seed-lings had typical auxin deficiency phenotypes with decreased height, curly leaves and shorten roots and petioles. The root length of GH3.17 overexpression seedlings was substantially increased by the application of low concentrations of indole acetic acid (IAA) or brassinolide (BL), and the overexpression plants were more sensitive to IAA and BR than the wild type plants. We also found that the expression of auxin signaling, and BR synthesis pathway-related genes IAA12 and IAA16 was inhibited in the overexpression plants , while the expression abundance of brassinosteroid biosynthetic genes DWF4 and CPD was increased, suggesting that the inhibition of auxin signal transduction caused by the deficiency of active auxin may be compensated by BR compounds accumulation.