Sucrose is an early modulator of the key hormonal mechanisms controlling bud outgrowth in Rosa hybrida

蔗糖是月季中控制芽生长的主要激素机制的早期调节因子

Abstract

Sugar has only recently been identified as a key player in triggering bud outgrowth, while hormonal control of bud outgrowth is already well established. To get a better understanding of sugar control, the present study investigated how sugar availability modulates the hormonal network during bud outgrowth in Rosa hybrida. Other plant models, for which mutants are available, were used when necessary.

激素控制芽生长的机制已经比较确定，但糖类只是最近才被发现的触发芽生长的关键因素。为了更好地了解糖类的调控机制，本研究探讨了月季花芽发育过程中，糖类如何有效调节激素网络。实验中也使用了其他可获得突变体的植物模型。

Buds were grown in vitro to manipulate available sugars. The temporal patterns of the hormonal regulatory network were assessed in parallel with bud outgrowth dynamics. Sucrose determined bud entrance into sustained growth in a concentration-dependent manner. Sustained growth was accompanied by sustained auxin production in buds, and sustained auxin export in a DR5::GUS-expressing pea line. Several events occurred ahead of sucrose-stimulated bud outgrowth.

通过体外培养控制芽对糖类的获取。对激素调节网络的时态模式与芽的生长活性进行并行评估。 蔗糖以浓度依赖性的方式决定芽的持续生长。在豌豆DR5::GUS表达株系中，持续的生长伴随着芽中生长素的持续产生和输出。几个事件都发生在蔗糖促进芽生长之前。

Sucrose upregulated early auxin synthesis genes (RhTAR1, RhYUC1) and the auxin efflux carrier gene RhPIN1, and promoted PIN1 abundance at the plasma membrane in a pPIN1::PIN1-GFP-expressing tomato line. Sucrose downregulated both RwMAX2, involved in the strigolactone-transduction pathway, and RhBRC1, a repressor of branching, at an early stage. The presence of sucrose also increased stem cytokinin content, but sucrose-promoted bud outgrowth was not related to that pathway. In these processes, several non-metabolizable sucrose analogues induced sustained bud outgrowth in R. hybrida, Pisum sativum, and Arabidopsis thaliana, suggesting that sucrose was involved in a signalling pathway.

在番茄pPIN1::PIN1-GFP表达株系中，蔗糖上调了早期生长素合成基因(RhTAR1, RhYUC1)，生长素携带RhPIN1基因外流，促进PIN1在质膜上富集。在早期阶段，蔗糖都下调了RwMAX2和RhBRC1的表达，RwMAX2参与独脚金内酯转导途径，而RhBRC1是其中一个分支的抑制子。蔗糖的存在同时也提高了细胞分裂素的含量，但蔗糖促进的芽的生长与该途径无关。在这些过程中，几种非代谢的蔗糖类似物促进了月季、豌豆和拟南芥中芽的持续生长，表明蔗糖参与了某个信号通路。

In conclusion, we identified potential hormonal candidates for bud outgrowth control by sugar. They are central to future investigations aimed at disentangling the processes that underlie regulation of bud outgrowth by sugar.

综上，作者确定了糖控制芽生长的潜在候选激素，它们将是未来研究糖类调控芽生长机制的重心。

Journal of Experimental Botany

François Barbier

Soulaiman Sakr(sakr@agrocampus-ouest.fr)

Université d’Angers法国昂热大学

https://doi.org/10.1093/jxb/erv047