State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Silviculture of the National Forestry and Grassland Administration, Chinese Academy of Forestry, Beijing 100091, China.
Experimental Center for Subtropical Forestry, Chinese Academy of Forestry, Xinyu 336600, China.
Int J Mol Sci. 2022 Oct 27;23(21):13021. doi: 10.3390/ijms232113021.
Floral initiation is a major phase change in the spermatophyte, where developmental programs switch from vegetative growth to reproductive growth. It is a key phase of flowering in tea-oil trees that can affect flowering time and yield, but very little is known about the molecular mechanism of floral initiation in tea-oil trees. A 12-year-old (cultivar 'changlin53') was the source of experimental materials in the current study. Scanning electron microscopy was used to identify the key stage of floral initiation, and transcriptome analysis was used to reveal the transcriptional regulatory network in old leaves involved in floral initiation. We mined 5 DEGs related to energy and 55 DEGs related to plant hormone signal transduction, and we found floral initiation induction required a high level of energy metabolism, and the phytohormones signals in the old leaves regulate floral initiation, which occurred at stage I and II. Twenty-seven rhythm-related DEGs and 107 genes associated with flowering were also identified, and the circadian rhythm interacted with photoperiod pathways to induce floral initiation. Unigene0017292 (), Unigene0046809 (), Unigene0009932 (), Unigene0001842 (), and Unigene0084708 () were the key genes in the circadian rhythm-photoperiod regulatory network. In conjunction with morphological observations and transcriptomic analysis, we concluded that the induction of floral initiation by old leaves in 'changlin53' mainly occurred during stages I and II, floral initiation was completed during stage III, and rhythm-photoperiod interactions may be the source of the main signals in floral initiation induced by old leaves.
花芽起始是种子植物的一个主要阶段变化，其中发育程序从营养生长转变为生殖生长。它是油茶开花的关键阶段，会影响开花时间和产量，但对于油茶花芽起始的分子机制知之甚少。本研究以一棵 12 年生的（品种为‘长林 53’）为实验材料来源。利用扫描电子显微镜确定花芽起始的关键阶段，并用转录组分析揭示老叶中参与花芽起始的转录调控网络。我们挖掘到了 5 个与能量相关的差异表达基因和 55 个与植物激素信号转导相关的差异表达基因，发现花芽起始诱导需要高水平的能量代谢，老叶中的植物激素信号调节花芽起始，发生在 I 期和 II 期。还鉴定到了 27 个节律相关的差异表达基因和 107 个与开花相关的基因，昼夜节律与光周期途径相互作用诱导花芽起始。Unigene0017292()、Unigene0046809()、Unigene0009932()、Unigene0001842()和 Unigene0084708()是昼夜节律-光周期调控网络中的关键基因。结合形态观察和转录组分析，我们得出结论，老叶诱导‘长林 53’花芽起始主要发生在 I 期和 II 期，III 期完成花芽起始，昼夜节律与光周期的相互作用可能是老叶诱导花芽起始的主要信号源。
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