Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, China.
Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, China; College of Life Science, Linyi University, Linyi, China.
Plant Sci. 2019 Mar;280:31-40. doi: 10.1016/j.plantsci.2018.11.009. Epub 2018 Nov 16.
Arabidopsis RACK1 (Receptors for Activated C Kinase 1) are versatile scaffold proteins that have been shown to be involved in the regulation of plant response to plant hormones including auxin, ABA, gibberellin and brassinosteroid, but not ethylene. By characterizing the double and triple mutants of RACK1 genes, we found that rack1 mutants showed reduced sensitivity to ethylene. By characterizing double and high order mutants generated between ein2, a loss-of-function mutant of the key ethylene signaling regulator gene EIN2 (Ethylene INsensitive 2), and rack1 mutants, we found that loss-of-function of EIN2 partially recovered some phenotypes observed in the rack1 mutants, such as low-fertility and reduced root length and rosette size. On the other hand, the ein2 rack1 mutants produced more rosette leaves, and flowered late when compared with ein2 and the corresponding rack1 mutants. We also found that the curled leaves and twisted petioles phenotypes observed in the ein2 mutants were enhanced in the ein2 rack1 mutants. However, assays in yeast indicated that EIN2 may not physically interact with RACK1. On the other hand, RT-PCR results showed that the expression level of EIN2 was reduced in the rack1 mutants. Taken together, our results suggest that RACKl may integrate ethylene signaling to regulate plant growth and development in Arabidopsis.
拟南芥 RACK1（激活蛋白激酶 C 的受体 1）是多功能支架蛋白，已被证明参与植物激素反应的调节，包括生长素、ABA、赤霉素和油菜素内酯，但不包括乙烯。通过对 RACK1 基因的双突变体和三突变体进行表征，我们发现 rack1 突变体对乙烯的敏感性降低。通过对乙烯信号调节关键基因 EIN2（Ethylene INsensitive 2）的功能丧失突变体 ein2 与 rack1 突变体之间产生的双突变体和更高阶突变体进行表征，我们发现 EIN2 的功能丧失部分恢复了 rack1 突变体中观察到的一些表型，例如低育性和根长和莲座叶大小降低。另一方面，与 ein2 和相应的 rack1 突变体相比，ein2 rack1 突变体产生了更多的莲座叶，并延迟开花。我们还发现，在 ein2 突变体中观察到的卷曲叶片和扭曲叶柄表型在 ein2 rack1 突变体中增强。然而，酵母中的测定表明 EIN2 可能不会与 RACK1 物理相互作用。另一方面，RT-PCR 结果表明，rack1 突变体中 EIN2 的表达水平降低。综上所述，我们的结果表明，RACK1 可能整合乙烯信号来调节拟南芥的生长和发育。
