陆地棉开花整合子调控机制解析

Investigation of Regulatory Mechanism of Floral Integrators in Upland Cotton

开花是植物产生有性生殖器官的重要阶段,开花整合子整合来自环境和植物体内的信号,进而激活花芽分化,使植物在适宜的时间产生足够多的后代,保障生殖繁衍。棉花中开花整合子基因(FT、SOC1和LFY)已被克隆,但它们在棉花中的进化关系尚不清楚。参考陆地棉基因组,明确了棉属开花整合子同源基因数目,FT和LFY在棉属中进化具有保守性,而SOC1基因序列具有多样性。不同于其他物种,棉花开花整合子基因均在顶端分生组织和叶片中表达量较高,且随着棉苗的生长发育其表达量逐步升高。克隆了GhLFY-2、GhFT-2和GhSOC1-5基因,发现其促进开花的功能是保守的,但开花时间调控机制存在物种特异性。陆地棉中既存在保守的GhFT-2/GhSOC1-5/GhLFY-2线性调控路径,又进化出GhFT-1和GhSOC1-1直接调控GhAP1的路径,表明棉花开花时间调控机制的多样性可能与其对环境的适应性有关。

Flowering is the important stage for plant to produce sexual organs.Floral integrators integrate the environmental and endogenous signals to ultimately activate floral transition at the appropriate time,enabling the plants to reproductive success.Although genes floral integrators(FT,SOC1 and LFY)have been cloned in cotton,their evolutionary relationship in tetraploid cotton remains unknown.In this study,the homologous of flowering integrators were identified through comparing the released cotton genomes.The results revealed that FT and LFY were evolutionally conserved among diploid and tetraploid cottons,while SOC1 displayed sequence diversity.Specifically,cotton flowering integrators displayed unified expression in leaf and shoot apical meristem with a gradual increase during seedling development.The unreported sequences GhLFY-2,GhFT-2 and GhSOC1-5 were cloned and overexpressed in Arabidopsis,resulting in conserved function of promoting floral transition.However,the regulatory mechanism between the flowering integrators was peculiar in cotton.There was a conserved GhFT-2/GhSOC1-5/GhLFY-2 linear regulatory pathway and a direct pathway in which GhFT-1 and GhSOC1-1 regulate GhAP1 independent of GhLFY.The diversity of flowering time regulation might associate with adaptation of cotton to the environment.