Fichtner Franziska, Barbier Francois F, Annunziata Maria G, Feil Regina, Olas Justyna J, Mueller-Roeber Bernd, Stitt Mark, Beveridge Christine A, Lunn John E
Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany.
School of Biological Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
New Phytol. 2021 Feb;229(4):2135-2151. doi: 10.1111/nph.17006. Epub 2020 Nov 25.
Trehalose 6-phosphate (Tre6P) is a sucrose signalling metabolite that has been implicated in regulation of shoot branching, but its precise role is not understood. We expressed tagged forms of TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) to determine where Tre6P is synthesized in arabidopsis (Arabidopsis thaliana), and investigated the impact of localized changes in Tre6P levels, in axillary buds or vascular tissues, on shoot branching in wild-type and branching mutant backgrounds. TPS1 is expressed in axillary buds and the subtending vasculature, as well as in the leaf and stem vasculature. Expression of a heterologous Tre6P phosphatase (TPP) to lower Tre6P in axillary buds strongly delayed bud outgrowth in long days and inhibited branching in short days. TPP expression in the vasculature also delayed lateral bud outgrowth and decreased branching. Increased Tre6P in the vasculature enhanced branching and was accompanied by higher expression of FLOWERING LOCUS T (FT) and upregulation of sucrose transporters. Increased vascular Tre6P levels enhanced branching in branched1 but not in ft mutant backgrounds. These results provide direct genetic evidence of a local role for Tre6P in regulation of axillary bud outgrowth within the buds themselves, and also connect Tre6P with systemic regulation of shoot branching via FT.
海藻糖6-磷酸（Tre6P）是一种蔗糖信号代谢物，与茎枝分枝的调控有关，但其确切作用尚不清楚。我们表达了带有标签的海藻糖-6-磷酸合酶1（TPS1）形式，以确定拟南芥（Arabidopsis thaliana）中Tre6P的合成位置，并研究了腋芽或维管组织中Tre6P水平的局部变化对野生型和分枝突变体背景下茎枝分枝的影响。TPS1在腋芽和下方维管系统以及叶和茎维管系统中表达。在腋芽中表达异源Tre6P磷酸酶（TPP）以降低Tre6P，在长日照下强烈延迟芽的生长，在短日照下抑制分枝。维管系统中TPP的表达也延迟了侧芽的生长并减少了分枝。维管系统中Tre6P的增加增强了分枝，并伴随着开花位点T（FT）的更高表达和蔗糖转运蛋白的上调。维管系统中Tre6P水平的增加增强了branched1中的分枝，但在ft突变体背景中没有。这些结果提供了直接的遗传学证据，证明Tre6P在芽自身内腋芽生长调控中的局部作用，并且还通过FT将Tre6P与茎枝分枝的系统调控联系起来。
