植物激素与年龄途径整合的分子机理

Physiological and genetic studies have demonstrated that plant growth and development are regulated not only by environmental signals such as day length, light intensity, and ambient temperature but also by endogenous signals transmitted by plant hormones and age. Although the underlying signaling transduction pathways have been extensively studied, how plant hormones are integrated into age pathway is largely unknown. In vitro plant regeneration occurs via two major pathways, de novo organogenesis and somatic embryogenesis, both of which are dependent on phytohormone perception, cell division and dedifferentiation to acquire organogenetic competence, organ initiation and development. The ratio of auxin and cytokinin guides the principle of in vitro organogenesis. A high cytokinin to auxin ratio induces shoot organogenesis, whereas opposite low ratio results in root development. We propose a project to investigate the crosstalk between age and auxin/cytokinin pathways by mulitiple approaches, such as genetics, transcriptomics, interactomics and functional genomics.

植物的生长发育受到外源和内源信号的共同调控。内源信号包括植物激素和年龄。虽然植物激素的信号转导机制已经研究的比较清楚，但是它们与植物年龄途径相互关系的研究至今还是一个空白。激素的响应与调控是否随植物体的年龄而变化，两条内源途径之间如何相互调节与整合都是亟待解决的生物学问题。植物组织再生与生长素和细胞分裂素密切相关。生长素和细胞分裂素的比例决定了组织的分化方向：生长素/细胞分裂素高时，有利于根的分化；生长素/细胞分裂素低时，有利于芽的分化。本课题立足于植物组织再生这一重要的生理过程，拟通过遗传学、细胞生物学和分子生物学等手段探究生长素和细胞分裂素与植物年龄途径之间的相互整合的分子机理。

植物的生长发育受到外源和内源信号的共同调控。内源信号包括植物激素和年龄。虽然植物激素的信号转导机制已经研究的比较清楚，但是它们与植物年龄途径相互关系的研究至今还是一个空白。本课题以植物组织为体系，通过遗传学、细胞生物学和分子生物学等手段研究了细胞分裂素与植物年龄途径相互整合调控植物茎尖再生率的分子机理。植物茎尖再生是由细胞分裂素信号传递途径的关键转录因子B-type ARR介导的。有趣的是，植物的茎尖再生能力伴随年龄增长而递减。年龄途径关键调控因子miR156的含量与植物再生能力呈正相关。随着植物年龄的增长，miR156的表达逐渐降低，导致了其靶基因SPL类转录因子含量的上升。高浓度的SPL可以与B-type ARR结合，导致B-type ARR的转录激活活性降低，进而引起植物茎尖再生能力的减弱。