IMB1, a bromodomain protein induced during seed imbibition, regulates ABA- and phyA-mediated responses of germination in Arabidopsis
IMB1, a bromodomain protein induced during seed imbibition, regulates ABA- and phyA-mediated responses of germination in Arabidopsis
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DOI：
10.1046/j.1365-313x.2003.01848.x
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发表时间：
2003-09-01
期刊：
影响因子：
7.2
通讯作者：
Chua, NH
中科院分区：
文献类型：
--
作者：
Duque, P;Chua, NH
我们报道了一种植物基因的特征，该基因编码溴结构域蛋白的BET亚群成员，溴结构域蛋白是一类新的推定转录因子。利用IMB1-黄色荧光蛋白（YFP）融合蛋白在洋葱表皮细胞的亚细胞定位表明，IMB1可能是一个核蛋白。在拟南芥中，IMB1在干燥种子中表达水平极低，但在种子吸胀过程中被显著诱导。此外，萌发过程中IMB1转录水平下调。功能缺失等位基因imb1的种子在ABA环境下萌发时子叶变绿受损，并且比野生型表达更高水平的ABI5蛋白。此外，imb1种子缺乏光敏色素A （phyA）介导的萌发极低通量响应。微阵列分析显示，包括不同功能类别的基因，如细胞壁代谢或质体功能，在吸收的imb1种子中受到抑制。突变体imb1植株表现正常，表明imb1参与调节一个特定的发育阶段。综上所述，这些结果表明IMB1分别通过负向和正向调节ABA和phyA转导通路来促进种子萌发。在被吸收的种子中，IMB1调节一系列基因的转录，为其作用方式提供线索。
We report the characterization of a plant gene encoding a member of the BET subgroup of bromodomain proteins, a novel class of putative transcription factors. Imbibition-inducible 1 (IMB1) appears to be a nuclear protein as suggested by subcellular localization in onion epidermal cells using an IMB1-yellow fluorescent protein (YFP) fusion protein. In Arabidopsis thaliana, IMB1 is expressed at very low levels in dry seeds, but is markedly induced during seed imbibition. In addition, IMB1 transcript levels are down regulated during germination. Seeds of a loss-of-function mutant allele, imb1, show impaired cotyledon greening during germination in abscisic acid (ABA) and express higher levels of ABI5 protein than the wild type. Moreover, imb1 seeds are deficient in the phytochrome A (phyA)-mediated very-low-fluence response of germination. Microarray analysis revealed that genes included in different functional categories, such as cell-wall metabolism or plastid function, are repressed in imbibed imb1 seeds. Mutant imb1 plants appear normal, indicating that IMB1 is involved in regulating a specific developmental stage. Taken together, these results show that IMB1 plays a role in the promotion of seed germination by both negatively and positively regulating the ABA and phyA transduction pathways, respectively. In imbibed seeds, IMB1 modulates the transcription of a battery of genes, providing clues on its mode of action.