Seo Mitsunori, Kanno Yuri, Frey Anne, North Helen M, Marion-Poll Annie
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, RD10, 78026 Versailles Cedex, France.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan.
Plant Sci. 2016 May;246:91-97. doi: 10.1016/j.plantsci.2016.02.013. Epub 2016 Feb 16.
Nine-cis-epoxycarotenoid dioxygenase (NCED) catalyzes the key step of abscisic acid (ABA) biosynthesis. There are five genes encoding NCED in Arabidopsis, which differentially regulate ABA biosynthesis in a spatiotemporal manner in response to endogenous and environmental stimuli. Previous studies have shown that NCED9 is expressed in testa and embryos during seed development. In the present study, we have identified promoter regions required for the expression of NCED9 in testa and embryos, respectively. Electrophoretic mobility shift assays (EMSA) and yeast one-hybrid (Y1H) assays showed that several homeodomain-leucine zipper (HD-Zip) proteins, namely ATHBs, bound to the sequence required for expression of NCED9 in testa, suggesting that they redundantly regulate NCED9 expression. By expressing the NCED9 gene under the control of a deleted NCED9 promoter in an nced9 mutant expression was limited to embryos. Transformants were complemented for the paclobutrazol resistant germination phenotype of the mutant, suggesting that the ABA synthesis mediated by NCED9 in embryos plays an important role in the regulation of gibberellin (GA)-dependent seed germination.
9-顺式环氧类胡萝卜素双加氧酶（NCED）催化脱落酸（ABA）生物合成的关键步骤。拟南芥中有五个编码NCED的基因，它们响应内源性和环境刺激，以时空方式差异调节ABA生物合成。先前的研究表明，NCED9在种子发育过程中在种皮和胚中表达。在本研究中，我们分别鉴定了种皮和胚中NCED9表达所需的启动子区域。电泳迁移率变动分析（EMSA）和酵母单杂交（Y1H）分析表明，几种同源异型域-亮氨酸拉链（HD-Zip）蛋白，即ATHBs，与种皮中NCED9表达所需的序列结合，表明它们冗余调节NCED9表达。通过在缺失的NCED9启动子控制下在nced9突变体中表达NCED9基因，其表达仅限于胚。转化体对突变体的多效唑抗性萌发表型具有互补作用，表明胚中由NCED9介导的ABA合成在赤霉素（GA）依赖性种子萌发的调节中起重要作用。
