CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA 5064, Australia.
Plant Physiol. 2021 Nov 3;187(3):1189-1201. doi: 10.1093/plphys/kiab237.
Dominance inhibition of shoot growth by fruit load is a major factor that regulates shoot architecture and limits yield in agriculture and horticulture crops. In annual plants, the inhibition of inflorescence growth by fruit load occurs at a late stage of inflorescence development termed the end of flowering transition. Physiological studies show this transition is mediated by production and export of auxin from developing fruits in close proximity to the inflorescence apex. In the meristem, cessation of inflorescence growth is controlled in part by the age-dependent pathway, which regulates the timing of arrest. Here, we show the end of flowering transition is a two-step process in Arabidopsis (Arabidopsis thaliana). The first stage is characterized by a cessation of inflorescence growth, while immature fruit continues to develop. At this stage, dominance inhibition of inflorescence growth by fruit load is associated with a selective dampening of auxin transport in the apical region of the stem. Subsequently, an increase in auxin response in the vascular tissues of the apical stem where developing fruits are attached marks the second stage for the end of flowering transition. Similar to the vegetative and floral transition, the end of flowering transition is associated with a change in sugar signaling and metabolism in the inflorescence apex. Taken together, our results suggest that during the end of flowering transition, dominance inhibition of inflorescence shoot growth by fruit load is mediated by auxin and sugar signaling.
果实负荷对生长的优势抑制是调节农业和园艺作物株型和限制产量的主要因素。在一年生植物中，由果实负荷引起的花序生长抑制发生在花序发育的晚期，称为花期转变结束。生理学研究表明，这种转变是由靠近花序顶端的发育果实中生长素的产生和输出介导的。在分生组织中，花序生长的停止部分由年龄依赖性途径控制，该途径调节停止的时间。在这里，我们表明，在拟南芥（Arabidopsis thaliana）中，花期转变结束是一个两步过程。第一阶段的特征是花序生长停止，而未成熟的果实继续发育。在这个阶段，果实负荷对花序生长的优势抑制与茎顶端区域生长素运输的选择性减弱有关。随后，附着在发育果实上的茎顶端血管组织中生长素反应的增加标志着花期转变结束的第二阶段。与营养生长和生殖生长的转变类似，花期转变结束与花序顶端糖信号和代谢的变化有关。综上所述，我们的结果表明，在花期转变结束期间，果实负荷对花序生长的优势抑制是由生长素和糖信号介导的。
