Xu Yan, Lv Zhengxin, Manzoor Muhammad Aamir, Song Linhong, Wang Maosen, Wang Lei, Wang Shiping, Zhang Caixi, Jiu Songtao
Department of Plant Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Road No. 800, Shanghai, 200240, P. R. China.
Mol Hortic. 2024 Oct 25;4(1):40. doi: 10.1186/s43897-024-00117-z.
The D14 protein, an alpha/beta hydrolase, is a key receptor in the strigolactone (SL) signaling pathway. However, the response of VvD14 to SL signals and its role in grapevine root architecture formation remain unclear. This study demonstrated that VvD14c was highly expressed in grapevine tissues and fruit stages than other VvD14 isoforms. Application of GR24, an SL analog, enhanced the elongation and diameter of adventitious roots but inhibited the elongation and density of lateral roots (LRs) and increased VvD14c expression. Additionally, GR24 is nested within the VvD14c pocket and strongly bound to the VvD14c protein, with an affinity of 5.65 × 10M. Furthermore, VvD14c interacted with grapevine MORE AXILLARY GROWTH 2 (VvMAX2) in a GR24-dependent manner. Overexpression of VvD14c in the d14 mutant and VvMAX2 in the max2 Arabidopsis mutant reversed the increased LR number and density, as well as primary root elongation. Conversely, homologous overexpression of VvD14c and VvMAX2 resulted in reduced LR number and density in grapevines. VvMAX2 directly interacted with LATERAL ORGAN BOUNDARY (VvLOB) and VvLBD19, thereby positively regulating LR density. These findings highlight the role of SLs in regulating grapevine root architecture, potentially via the VvD14c-VvMAX2-VvLOB/VvLBD19 module, providing new insights into the regulation of root growth and development in grapevines.
D14蛋白是一种α/β水解酶，是独脚金内酯（SL）信号通路中的关键受体。然而，VvD14对SL信号的响应及其在葡萄根系结构形成中的作用仍不清楚。本研究表明，VvD14c在葡萄组织和果实发育阶段的表达高于其他VvD14异构体。施用SL类似物GR24可促进不定根的伸长和增粗，但抑制侧根（LRs）的伸长和密度，并增加VvD14c的表达。此外，GR24嵌套在VvD14c口袋内，并与VvD14c蛋白紧密结合，亲和力为5.65×10M。此外，VvD14c以GR24依赖的方式与葡萄多腋芽生长2（VvMAX2）相互作用。在d14突变体中过表达VvD14c以及在拟南芥max2突变体中过表达VvMAX2可逆转LR数量和密度的增加以及主根伸长。相反，在葡萄中同源过表达VvD14c和VvMAX2会导致LR数量和密度降低。VvMAX2直接与侧器官边界（VvLOB）和VvLBD19相互作用，从而正向调节LR密度。这些发现突出了SLs在调节葡萄根系结构中的作用，可能是通过VvD14c-VvMAX2-VvLOB/VvLBD19模块，为葡萄根系生长和发育的调控提供了新的见解。
