Research on the regulation of gibberellin receptors

拟南芥携带三种植物激素赤霉素（GA）的受体基因，AtGID 1a，AtGID 1b和AtGID 1c。每个基因的表达在水稻gid 1 -1突变体的GA受体恢复其严重矮化表型和GA不敏感性到正常水平，即使每个功能丧失突变体在拟南芥中没有明确的表型。我们通过分析多个突变体的功能丧失突变，报告了每个AtGID 1的功能冗余和特异性。双KO突变体atgid 1a + atgid 1b、atgid 1a + atgid 1c和atgid 1b + atgid 1c的种子正常发芽。双KO突变体atgid 1a + atgid 1c表现出侏儒表型，而其他双突变体具有与野生型相当的正常高度。双KO突变体atgid 1a + atgid 1b的雄蕊比野生型的雄蕊短得多，这导致其育性低，还观察到其种子表面的图案严重紊乱。三重KO突变体atgid 1a + atgid 1b + atgid 1c不能自发萌发，只有在浸泡后剥去种皮才能开始生长。三重KO突变体的幼苗在生长一个月后为几毫米高的严重矮化。此外，三重KO幼苗完全丧失了对外源施加的GA的响应能力。这些结果表明，所有AtGID 1 s功能作为GA受体在拟南芥中，并部分具有特定的作用（S）的生长和发育。

Arabidopsis carries three receptor genes for the phytohormone gibberellin (GA), AtGID1a, AtGID1b, and AtGID1c. The expression of each gene in the rice gid1-1 mutant for GA-receptor reverts its severely dwarfed phenotype and GA-insensitivity to a normal level, even though each loss-of-function mutant shows no clear phenotype in Arabidopsis. We report the functional redundancy and specificity of each AtGID1 by analyzing the multiple mutants for loss-of-function mutation. Seeds of double KO mutants, atgid1a+atgid1b, atgid1a+atgid1c, and atgid1b+atgid1c, normally germinated. The double KO mutant, atgid1a+atgid1c showed a dwarf phenotype, while other double mutants had a normal height comparable to the wild type. Stamens of the double KO mutant, atgid1a+atgid1b are significantly much shorter than those of wild type, and this leads to low fertility A severe disarrangement of the pattern on its seed surface was also observed. The triple KO mutant, atgid1a+atgid1b+atgid1c did not germinate voluntarily, but could only start to grow when the seed coat was peeled off after soaking. Seedlings of the triple KO mutants were severe dwarfs several millimeters high after growing for one month. Moreover the triple KO seedlings completely lost their ability to respond to exogenously applied GA. These results show that all AtGID1s function as GA receptors in Arabidopsis, and in part have specific role(s) for growth and development.