收稿日期:2020-09-11 录用日期:2021-04-17
基金项目:福建省交通运输科技项目(201821)
通信作者:chenzl135@126.com(陈自亮); appo@xmu.edu.cn(纪志梁)
基金项目:福建省交通运输科技项目(201821)
通信作者:chenzl135@126.com(陈自亮); appo@xmu.edu.cn(纪志梁)
三角梅(Bougainvillea spectabilis wind)是一种在热带、亚热带地区广泛分布的观赏性藤本状灌木.选取同安红三角梅品种(Miss Manila)为研究对象,测定其在成花早期组织器官形态变化过程中19种内源激素或激素前体的动态变化,并开展激素之间的相关性分析和互作网络化分析.结果显示:赤霉素4(GA4)、GA7、顺式-12-氧-植物二烯酸(cis-OPDA)、脱落酸(ABA)、反式玉米素(tZ)、反式玉米素核苷(tzR)、油菜素甾酮(CS)和1-氨基环丙烷羧酸(ACC)等激素或前体水平都在三角梅花芽分化初期有大幅度的提升.其中,GA7的水平在未分化期→花芽分化初期(刺→花刺)升高了1 388%,并在花芽分化的不同时期都保持较高水平,说明高水平的GA7对三角梅成花具有促进作用.进一步分析表明,高浓度的ABA、tzR和ACC只特异性在三角梅侧端成花中显著高表达,二氢玉米素(DHZ)和水杨酸(SA)则特异地参与三角梅顶端成花的分化; 这些激素可能应用于三角梅的选择性开花调控.综上可见GA7、cis-OPDA、GA4和tZ可能作为节点激素在三角梅开花早期扮演着关键调控角色,可为深入理解三角梅开花的分子机制以及在生产实践中实现三角梅的精准花期调控提供参考.
Objective s: Bougainvillea spectabilis is an ornamental vine shrub widely distributed in tropical and subtropical areas. Hormone regulation is a common chemical way to interfere with B. spectabilis flowering in practices. However, the regulation efficiency is largely limited by poor knowledge of hormone behavior during the flowering.
Methods : In this study, B. spectabilis Miss Manila, a variety commonly used in road landscape construction, was selected as the research object to trace and determine the dynamic changes of 19 endogenous hormones or hormone precursors during the morphological changes of tissues inan early flowering stage. Correlation analysis and interaction network analysis were also carried out between hormones. The tissues samples collected from the pot-culture Bougainvillea were divided into three groups according to the collection position, with the small leaf as a control, the lateral flowering group (tissue samples of thorn, bud, and bud of about to bloom), and the top flowering group (tissue samples of leaf sprout, bud, bud of about to bloom). The hormone contents of the samples were determined using liquid chromatography and mass spectrometry. The difference between hormone contents was assessed by calculating the coefficient of variation (CV), and the correlation between the changes of hormone levels was also analyzed. Furthermore, the interaction network of hormones was constructed according to the hormone correlation during the flowering with Cytoscape software, from which the hub nodes were identified as the key hormones in the process.
Results : The results showed that the contents of gibberellin A4(GA4), GA7, cis 12-oxo-phytic acid(cis-OPDA), abscisic acid(ABA), trans-zein(tZ), trans-zeatin nucleoside(tzR), brassinosteroid(CS), and 1-amino-cyclopropane-1-carboxylic acid(ACC) increased significantly at the early stage of flower-bud differentiation. In particular, GA7 increased by 1,388% during the thorn-to-bud transition and maintained the high level at different stages of flowering, indicating that the high content of GA7 could be crucial to the flowering of B. spectabilis. In addition, GA4, dihydrozeatin(DHZ), tZ, GA7, cis-OPDA, ABA, CS, tzR, and ACC fluctuated significantly in the lateral flowering; in the top flowering process, tZ and CS, GA4 and salicylic acid(SA), GA7, cis-OPDA, and DHZ changed significantly. These hormones were likely involved in respective flowering process. Via correlation analysis of hormone fluctuations during the lateral flowering, we identified two clusters, within which the hormones were all positively correlated with each other (coefficient≥0.85), one cluster of five hormones (GA4, DHZ, tZ, GA7 and cis-OPDA) and the other cluster of four hormones (ABA, CS, tzR and ACC). In the apical flowering study, we obtained three clusters on the basis of seven fluctuating hormones, one cluster of two hormones (tZ and CS), one cluster of two hormones (GA4 and SA), and one cluster of three hormones (GA7, cis-OPDA and DHZ). Noteworthy, the hormone fluctuation of tZ-CS cluster exhibited antagonistic performance in the top flowering process with the GA4-SA cluster. Subsequent network analysis further extracted four hub nodes (GA7, cis-OPDA, GA4 and tZ), which likely played key regulatory roles in the early flowering of B. spectabilis.
Conclusion s: In this study, we depicted the hormone dynamic landscapes at different flowering stages of B. spectabilis, from which we found that GA1, GA4, GA7, cis-OPDA, ABA, SA, tZ, DHZ, tzR, CS and ACC might be anticipated in the early regulation of flowering. In general, increases of GA7, cis-OPDA, tZ and CS could promote flower-bud differentiation. Particularly, increases of ABA, tzR and ACC would be beneficial for lateral flowering, while an increase of DHZ and decreases of SA and GA4 could promote the top flowering. Last but not the least, we specified that GA7, cis-OPDA, GA4 and tZ likely served as the hub hormones in the early flowering of B. spectabilis. Therefore, this study will reinforce current molecular understanding of B. spectabilis flowering by providing comprehensive information of hormone dynamics. It also provides data clues for precise chemical regulation of B. spectabilis flowering.
