Rabdosinate调节生长素极性运输蛋白PIN1、PIN3和PIN4抑制拟南芥幼苗根生长

利用3种拟南芥生长素极性运输外运载体突变体及4种转基因株系研究了二萜rabdosinate抑制拟南芥幼苗主根及侧根生长的作用机制。结果显示，60~80 μmol·L^-1的rabdosinate显著抑制野生型拟南芥幼苗主根生长及侧根形成，而对突变体pin1、pin2和pin3主根未显示明显的抑制效应，对侧根的抑制减弱；发现rabdosinate （60~80 μmol·L^-1）引起生长素报告株系根尖DR5活性升高，并增加融合蛋白PIN1-GFP丰度以及减少PIN3-GFP和PIN4-GFP的丰度。推断rabdosinate可通过增加PIN1丰度促进了根部生长素向顶运输，而减少PIN3丰度降低根尖部生长素的横向转运，引起了生长素在根尖部的累积及生长素浓度梯度的改变，进而抑制幼苗主根生长及侧根发育。

Rabdosinate Regulates Polar Auxin Carriers PIN1,PIN3 and PIN4 and Inhibits Root Growth of Arabidopsis thaliana Seedlings

This paper studied the mechanism of inhibition of primary root growth and lateral root development regulated by rabdosinate using polar auxin carriers reporter lines(PIN1::PIN1:GFP,PIN3::PIN3:GFP,PIN4::PIN4:GFP) and auxin reporters line(DR5::DR5:GFP). The results showed that the length of primary root and the number of lateral root in wild-type Arabidopsis thaliana seedlings were significantly reduced by 60~80 μmol·L^-1 rabdosinate. However, the mutants pin1, pin3 and pin4 showed a lower level of sensitivity to rabdosinate in terms of the inhibition of root elongation and lateral root formation compared with the WT seedlings.Rabdosinate(60~80 μmol·L^-1)induced a dose-dependent increase in DR5 activity and the abundance of PIN1-GFP fusion proteins in the root tips of A.thaliana, and significantly decreased the abundance of PIN3-GFP and PIN4-GFP at their respective cellular locations. These results suggest that rabdosinate may promote acropetal auxin transport activities by increasing the abundance of PIN1 and block transverse auxin transport activities by decreasing the abundance of PIN3-GFP and PIN4-GFP, resulting in auxin accumulation in the root meristematic cells and the inhibition of root growth and lateral root development.