Research on the regulation of gibberellin receptors

拟南芥携带三种植物激素赤霉素（GA）受体基因：AtGID1a、AtGID1b和AtGID1c。水稻ga受体gid1-1突变体中每个基因的表达将其严重矮化的表型和ga不敏感恢复到正常水平，尽管每个功能缺失的突变体在拟南芥中没有明确的表型。我们通过分析功能缺失突变的多个突变体，报告了每个AtGID1的功能冗余和特异性。双KO突变体atgid1a+atgid1b、atgid1a+atgid1c和atgid1b+atgid1c的种子正常发芽。双KO突变体atgid1a+atgid1c表现为矮化表型，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atgid1a+atgid1b的雄蕊明显短于野生型，这导致其育性较低，其种子表面图案严重紊乱。三重KO突变体atgid1a+atgid1b+atgid1c不主动发芽，只有在浸泡后剥去种皮后才能开始生长。三KO突变体的幼苗在生长一个月后就变成了几毫米高的严重侏儒。此外，三重KO幼苗完全丧失了对外源GA的响应能力。这些结果表明，所有atgid1在拟南芥中都具有GA受体的功能，并且在一定程度上对生长发育具有特定的作用。

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.