Joint International Research Laboratory of Water and Nutrient in Crops and College of Resource and Environment, Center for Plant Water-Use and Nutrition Regulation and College of Life Sciences, Fujian Agriculture and Forestry University, Jinshan, Fuzhou 350002, China.
Basic Forestry and Proteomics Research Center, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Science, Fujian Agriculture and Forestry University, Jinshan, Fuzhou 350002, China.
Int J Mol Sci. 2022 Mar 31;23(7):3846. doi: 10.3390/ijms23073846.
Root hydrotropism refers to root directional growth toward soil moisture. Cortical microtubule arrays are essential for determining the growth axis of the elongating cells in plants. However, the role of microtubule reorganization in root hydrotropism remains elusive. Here, we demonstrate that the well-ordered microtubule arrays and the microtubule-severing protein KATANIN (KTN) play important roles in regulating root hydrotropism in Arabidopsis. We found that the root hydrotropic bending of the mutant was severely attenuated but not root gravitropism. After hydrostimulation, cortical microtubule arrays in cells of the elongation zone of wild-type (WT) Col-0 roots were reoriented from transverse into an oblique array along the axis of cell elongation, whereas the microtubule arrays in the mutant remained in disorder. Moreover, we revealed that abscisic acid (ABA) signaling enhanced the root hydrotropism of WT and partially rescued the oryzalin (a microtubule destabilizer) alterative root hydrotropism of WT but not mutants. These results suggest that katanin-dependent microtubule ordering is required for root hydrotropism, which might work downstream of ABA signaling pathways for plant roots to search for water.
根向水生长是指根朝着土壤水分的方向生长。皮层微管阵列对于确定植物伸长细胞的生长轴至关重要。然而，微管重组在根向水生长中的作用仍然难以捉摸。在这里，我们证明了有序的微管阵列和微管切断蛋白 KATANIN（KTN）在调节拟南芥根向水生长中发挥重要作用。我们发现，突变体的根向水弯曲严重减弱，但根向地性没有减弱。在水力刺激后，野生型（WT）Col-0 根伸长区细胞的皮层微管阵列从横向重新定向为沿细胞伸长轴的斜向排列，而突变体的微管阵列仍然无序。此外，我们揭示了脱落酸（ABA）信号增强了 WT 的根向水生长，并部分挽救了野尻霉素（一种微管解稳定剂）对 WT 的替代根向水生长，但不能挽救突变体。这些结果表明，katanin 依赖性微管有序是根向水生长所必需的，这可能是植物根系寻找水分的 ABA 信号通路的下游作用。
