Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Lorey I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Proc Natl Acad Sci U S A. 2019 Aug 6;116(32):16127-16136. doi: 10.1073/pnas.1906405116. Epub 2019 Jul 19.
Florigen, a proteinaceous hormone, functions as a universal long-range promoter of flowering and concurrently as a generic growth-attenuating hormone across leaf and stem meristems. In flowering plants, the transition from the vegetative phase to the reproductive phase entails the orchestration of new growth coordinates and a global redistribution of resources, signals, and mechanical loads among organs. However, the ultimate cellular processes governing the adaptation of the shoot system to reproduction remain unknown. We hypothesized that if the mechanism for floral induction is universal, then the cellular metabolic mechanisms underlying the conditioning of the shoot system for reproduction would also be universal and may be best regulated by florigen itself. To understand the cellular basis for the vegetative functions of florigen, we explored the radial expansion of tomato stems. RNA-Seq and complementary genetic and histological studies revealed that florigen of endogenous, mobile, or induced origins accelerates the transcription network navigating secondary cell wall biogenesis as a unit, promoting vascular maturation and thereby adapting the shoot system to the developmental needs of the ensuing reproductive phase it had originally set into motion. We then demonstrated that a remarkably stable and broadly distributed florigen promotes and genes, which in turn regulate the rate of vascular maturation and radial expansion of stems irrespective of flowering or florigen level. The dual acceleration of flowering and vascular maturation by florigen provides a paradigm for coordinated regulation of independent global developmental programs.
成花素作为一种蛋白类激素，在植物中充当通用的远距离开花促进因子，同时在叶片和茎尖分生组织中作为通用的生长减缓激素。在开花植物中，从营养生长阶段向生殖生长阶段的转变需要协调新的生长坐标，并在器官之间重新分配信号、资源和机械负载。然而，控制营养器官系统适应生殖的最终细胞过程仍不清楚。我们假设，如果花诱导的机制是普遍的，那么为生殖而调节营养器官系统的细胞代谢机制也应该是普遍的，并且可能最好由成花素来调节。为了了解成花素的营养功能的细胞基础，我们探索了番茄茎的径向扩张。RNA-Seq 及互补的遗传和组织学研究表明，内源的、移动的或诱导的成花素加速转录网络作为一个整体导航次生细胞壁生物发生，促进血管成熟，从而使营养器官系统适应其最初启动的后续生殖阶段的发育需求。然后，我们证明了一种非常稳定且广泛分布的成花素促进 和 基因的表达，而这些基因又反过来调节血管成熟和茎的径向扩张的速度，而不论是否开花或成花素水平如何。成花素对开花和血管成熟的双重加速为协调独立的全球发育程序的调控提供了范例。
