College of life sciences, South China Agricultural University, Guangzhou, 510642, China.
Guangdong Engineering Polytechnic, Guangzhou, 510520, China.
Sci Rep. 2017 Mar 31;7:45748. doi: 10.1038/srep45748.
Vernalization is required for floral initiation in Dendrobium. Interestingly, those beneficial effects can also be achieved by exogenous cytokinin application in greenhouses. Thus, an as yet unknown crosstalk/interaction may exist between vernalization and cytokinin signaling pathways. In this study, we showed, by de novo transcriptome assembly using RNA-seq data from both vegetative and reproductive tissue samples, that some floral transition-related genes-DnVRN1, FT, SOC1, LFY and AP1-were differentially expressed in low-temperature-challenged (LT) or thidiazuron (TDZ)-treated plants, compared to those mock-treated (CK). Both LT and TDZ upregulated SOC1, LFY and AP1, while the upregulation of DnVRN1 and FT was only LT-induced. We further found that LT promoted the upregulation of some key cytokinin signaling regulators, including several cytokinin biosynthesis-related genes and type-B response regulator (RR)-encoding genes, and that both LT and TDZ triggered the significant upregulation of some marker genes in the gibberellin (GA) signaling pathway, indicating an important low temperature-cytokinin-GA axis in flowering. Our data thus have revealed a cytokinin-GA signal network underlying vernalization, providing a novel insight into further investigation of the molecular mechanism of floral initiation in Dendrobium.
春花作用是铁皮石斛开花所必需的。有趣的是，在温室中应用细胞分裂素也可以达到这些有益的效果。因此，春花作用和细胞分裂素信号通路之间可能存在尚未被发现的串扰/相互作用。在这项研究中，我们通过对来自营养组织和生殖组织样本的 RNA-seq 数据进行从头转录组组装，表明一些与花发育相关的基因-DnVRN1、FT、SOC1、LFY 和 AP1-在低温处理（LT）或噻苯隆（TDZ）处理的植物中与对照（CK）相比差异表达。LT 和 TDZ 均上调了 SOC1、LFY 和 AP1，而 DnVRN1 和 FT 的上调仅受 LT 诱导。我们进一步发现 LT 促进了一些关键细胞分裂素信号调节因子的上调，包括几个细胞分裂素生物合成相关基因和 B 型反应调节剂（RR）编码基因，并且 LT 和 TDZ 均触发了赤霉素（GA）信号通路中一些标记基因的显著上调，表明在开花过程中存在一个重要的低温-细胞分裂素-GA 轴。因此，我们的数据揭示了一个细胞分裂素-GA 信号网络，为进一步研究铁皮石斛开花的分子机制提供了新的视角。
