Light-Regulated Hypocotyl Elongation Involves Proteasome-Dependent Degradation of the Microtubule Regulatory Protein WDL3 in Arabidopsis
Light-Regulated Hypocotyl Elongation Involves Proteasome-Dependent Degradation of the Microtubule Regulatory Protein WDL3 in Arabidopsis
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DOI：
10.1105/tpc.113.112789
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发表时间：
2013-05-01
期刊：
影响因子：
11.6
通讯作者：
Mao, Tonglin
中科院分区：
文献类型：
--
作者：
Liu, Xiaomin;Qin, Tao;Mao, Tonglin
光显着抑制下胚轴细胞伸长，黑暗生长的幼苗表现出伸长，黄化的下胚轴。微管调节蛋白作为正或负调节因子，通过改变微管组织来介导下胚轴细胞的伸长。然而，目前还不清楚植物如何协调这些调节剂，以促进下胚轴在黑暗中的生长和抑制生长的光。在这里，我们证明了WAVE-DAMPENED 2-LIKE 3（WDL 3），一个微管调节蛋白的WVD 2/WDL家族从拟南芥，功能在下胚轴细胞伸长和调节的泛素-26 S蛋白酶体依赖性途径响应于光。WDL 3 RNA干扰拟南芥幼苗生长在光下有更长的下胚轴比对照。此外，WDL 3过表达导致下胚轴细胞的整体缩短和皮层微管在光照下的稳定。皮层微管重组发生缓慢，从WDL 3 RNA干扰转基因株系的细胞，但加速从WDL 3过表达的幼苗进行光处理的细胞。更重要的是，WDL 3蛋白在光照下丰富，但在黑暗中通过26 S蛋白酶体途径降解。WDL 3的过表达抑制了调控颗粒非ATP酶亚基-1a突变体（rpn 1a-4）植物的黄化下胚轴生长，但在野生型幼苗中没有。因此，泛素-26S蛋白酶体依赖性机制调节WDL 3水平以响应光来调节下胚轴细胞伸长。
Light significantly inhibits hypocotyl cell elongation, and dark-grown seedlings exhibit elongated, etiolated hypocotyls. Microtubule regulatory proteins function as positive or negative regulators that mediate hypocotyl cell elongation by altering microtubule organization. However, it remains unclear how plants coordinate these regulators to promote hypocotyl growth in darkness and inhibit growth in the light. Here, we demonstrate that WAVE-DAMPENED 2-LIKE3 (WDL3), a microtubule regulatory protein of the WVD2/WDL family from Arabidopsis thaliana, functions in hypocotyl cell elongation and is regulated by a ubiquitin-26S proteasome-dependent pathway in response to light. WDL3 RNA interference Arabidopsis seedlings grown in the light had much longer hypocotyls than controls. Moreover, WDL3 overexpression resulted in overall shortening of hypocotyl cells and stabilization of cortical microtubules in the light. Cortical microtubule reorganization occurred slowly in cells from WDL3 RNA interference transgenic lines but was accelerated in cells from WDL3-overexpressing seedlings subjected to light treatment. More importantly, WDL3 protein was abundant in the light but was degraded through the 26S proteasome pathway in the dark. Overexpression of WDL3 inhibited etiolated hypocotyl growth in regulatory particle non-ATPase subunit-1a mutant (rpn1a-4) plants but not in wild-type seedlings. Therefore, a ubiquitin-26S proteasome-dependent mechanism regulates the levels of WDL3 in response to light to modulate hypocotyl cell elongation.