Leukamenin E调节拟南芥幼苗根部生长素极性运输及根系生长发育

Regulation of leukamenin E on polar auxin transport and root growth and development in Arabidopsis thaliana seedlings

本文采用14种拟南芥转基因报告株系,研究了对映-贝壳杉烷二萜(leukamenin E)调节拟南芥根部生长素极性运输转运蛋白表达并影响根生长发育的机制。结果表明:leukamenin E浓度在20~40μmol·L-1范围显著抑制拟南芥幼苗主根的生长,较低浓度leukamenin E(10μmol·L-1)促进侧根提前发生并增加侧根数量;10~30μmol·L-1的leukamenin E在处理拟南芥幼苗48 h后可显著提高其根尖部生长素水平;进一步检测根部生长素极性运输转运蛋白表达,发现该浓度条件下leukamenin E促进PIN1在转录水平表达并增加其蛋白丰度,但在转录水平抑制PIN2表达并减少其蛋白丰度;同时,显著减少PIN3、PIN7和PIN4蛋白在小柱和静止中心及其周围细胞的丰度以及AUX1的定位丰度;Leukamenin E对PIN1丰度的上调以及对PIN2、PIN3、PIN4、PIN7和AUX1定位丰度的减少可导致生长素在根尖顶部的积累以及根部生长素浓度梯度的改变,引起根生长的抑制及侧根的提前发生。

We used 14 Arabidopsis thaliana transgenic reporter lines to investigate the mechanism of leukamenin E regulating the expression of polar auxin carriers and affecting root growth and development.The results showed that leukamenin E within 20-40μmol·L-1 significantly inhibited the growth of primary roots of A.thaliana seedlings.However,low concentration of leukamenin E(10μmol·L-1)promoted the early occurrence of lateral roots and increased the number of lateral roots.Leukamenin E significantly increased auxin level in the root apex at 10-30μmol·L-1 for 48 h.Furthermore,we investigated the role of leukamenin E in response to polar auxin transport proteins in A.thaliana roots.The results showed that expression of PIN1 was up-regulated and expression of PIN2 was down-regulated at the transcriptional and protein level by leukamenin E.The abundance of PIN3,PIN7,and PIN4 were obviously reduced in the columella cells and the quiescent center and surrounding cells.The abundance of AUX1 was decreased in the epidermis and lateral root cap cells.These results suggest that auxin accumulation in the root apex through regulation of polar auxin carriers had inhibitory effects on primary roots and early formation of lateral roots.