Present address: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, People's Republic of China.
Present address: State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, People's Republic of China.
BMC Plant Biol. 2020 Mar 6;20(1):105. doi: 10.1186/s12870-020-2303-z.
"Bairihua", a variety of the Catalpa bungei, has a large amount of flowers and a long flowering period which make it an excellent material for flowering researches in trees. SPL is one of the hub genes that regulate both flowering transition and development.
SPL homologues CbuSPL9 was cloned using degenerate primers with RACE. Expression studies during flowering transition in "Bairihua" and ectopic expression in Arabidopsis showed that CbuSPL9 was functional similarly with its Arabidopsis homologues. In the next step, we used Y2H to identify the proteins that could interact with CbuSPL9. HMGA, an architectural transcriptional factor, was identified and cloned for further research. BiFC and BLI showed that CbuSPL9 could form a heterodimer with CbuHMGA in the nucleus. The expression analysis showed that CbuHMGA had a similar expression trend to that of CbuSPL9 during flowering in "Bairihua". Intriguingly, ectopic expression of CbuHMGA in Arabidopsis would lead to aberrant flowers, but did not effect flowering time.
Our results implied a novel pathway that CbuSPL9 regulated flowering development, but not flowering transition, with the participation of CbuHMGA. Further investments need to be done to verify the details of this pathway.
梓树是梓属植物的一种，具有大量的花朵和较长的花期，是树木开花研究的优良材料。SPL 是调控开花转变和发育的枢纽基因之一。
使用 RACE 用简并引物克隆了 SPL 同源物 CbuSPL9。在“Bairihua”的开花转变过程中的表达研究和在拟南芥中的异位表达表明，CbuSPL9 的功能与其拟南芥同源物相似。下一步，我们使用 Y2H 来鉴定可以与 CbuSPL9 相互作用的蛋白质。鉴定并克隆了结构转录因子 HMGA 以进行进一步研究。BiFC 和 BLI 表明，CbuSPL9 可以在核内与 CbuHMGA 形成异二聚体。表达分析表明，CbuHMGA 在“Bairihua”开花过程中的表达趋势与 CbuSPL9 相似。有趣的是，CbuHMGA 在拟南芥中的异位表达会导致异常的花朵，但不会影响开花时间。
我们的结果表明，CbuSPL9 与 CbuHMGA 一起参与调控开花发育，但不调控开花转变的新途径。需要进一步投资来验证该途径的细节。
