文冠果花芽分化过程及内源激素动态变化

【目的】研究文冠果花芽分化过程外部形态变化与内部解剖结构的对应关系,并探究内源激素含量与花芽分化的关系,为文冠果花性别相关研究的适时采样与提高雌/雄花比例的调控技术提供参考。【方法】通过外部形态观测,结合石蜡切片技术,分析文冠果花芽分化内外部形态之间的对应关系。并采用高效液相色谱法(HPLC)对花芽分化过程中雌、雄能花的4种内源激素含量进行测定和比较,探究其与内源激素之间的关系。【结果】① 文冠果雌能花和雄能花在性别分化之前均为两性,雌能花的单核花粉粒在有丝分裂期呈液泡化衰败,雄能花大孢子母细胞四分体时期细胞停止分裂,性器官发育异常导致单性花的形成。此外,文冠果花芽分化内部结构与外部形态之间具有时序性对应关系。② 玉米素(zeatin,ZT)含量在花芽未分化期至雌蕊原基分化期逐渐上升,雌雄配子体形成时期,雌能花的ZT含量始终高于雄能花。雌能花雄蕊发育出现异常时的生长素(auxin,IAA)、胞落酸(abscisic acid,ABA)含量显著高于雄能花,赤霉素(gibberellin,GA)含量显著低于雄能花。说明高水平ZT促进花芽分化,利于雌能花的发育; 高水平的IAA和ABA具有促雌作用; 高水平的GA具有促雄效应。③ m(ABA)/m(IAA)、m(ABA)/m(GA)、m(ZT)/m(GA)在花芽未分化期至雌蕊原基分化期均处于较高水平,雄能花雌蕊发育异常时,其m(ABA)/m(IAA)和m(ZT)/m(IAA)显著高于雌能花。说明高水平的m(ABA)/m(IAA)、m(ABA)/m(GA)、m(ZT)/m(GA)有利于花芽分化; 高水平m(ABA)/m(IAA)、m(ZT)/m(IAA)对雄蕊发育有利。【结论】文冠果雌能花和雄能花各自对应另一性器官的败育导致了性别分化。花芽分化过程中,可以根据花芽外部形态判断内部分化时期。高水平的ZT含量、m(ABA)/m(IAA)、m(ABA)/m(GA)、m(ZT)/m(GA)利于花芽分化,高水平的m(ZT)、m(IAA)和m(ABA)利于雌能花发育,高水平的GA含量、m(ABA)/m(IAA)、m(ZT)/m(IAA)利于雄能花发育。

Flower bud differentiation and dynamic changes of endogenous hormone in Xanthoceras sorbifolium Bunge

【Objective】 The objective of this study is to study the relationship between external morphology and internal anatomical structure of flower buds during flower bud differentiation, and the relationship between hormones content and flower bud differentiation in Xanthoceras sorbifolium Bunge. The results will provide reference for the timely sampling in the study of X. sorbifolium Bunge flower sex and the regulation techniques used to increase the ratio of female to male flowers. 【Method】 Through the external morphology observation, combined with the paraffin sections, the correspondence between the internal and external morphology of the flower bud differentiation process was analyzed. To study the relationship between hormones content and flower bud differentiation in X. sorbifolium Bunge, four kinds of endogenous hormones in female flowers and male flowers were determined by HPLC. 【Result】 Both the female flowers and male flowers were bisexual before sex differentiation. There was vacuolization in mononuclear pollen grains during mitosis stage in female flowers, and the megaspore mother cell stopped dividing during the tetrad stage in male flowers. As a result, the abnormal development of sexual organs caused the formation of a unisexual flower. In addition, there was a temporal correspondence between the internal structure and the external morphology of flower buds. The zeatin(ZT)content increased gradually during the stage from flower bud undifferentiated period to pistil primordium differentiation. During male and female gametophyte formation period, the ZT content of female flowers was always higher than those of the male flowers. The IAA and ABA contents of female flowers were significantly higher than those of the male flowers when the stamens of female flowers developed abnormally, and the GA content was significantly lower than those of the male flowers. It is indicated that high levels of ZT can promote flower bud differentiation, and was beneficial to the development of female flowers. High levels of the IAA and ABA had a promoting effect on female flowers formation, and high levels of the GA promoted the development of male flowers. The ratios of m(ABA)to m(IAA), m(ABA)to m(GA), and m(ZT)to m(GA)were at a high level during the period from flower bud undifferentiated period to pistil primordium differentiation. When male flower pistil dysplasia was abnormal, the ratios of m(ABA)to m(IAA)and m(ZT)to m(IAA)of male flowers were significantly higher than that in females, indicating that high levels of the ratios of m(ABA)to m(IAA), m(ABA)to m(GA), and m(ZT)to m(GA)were beneficial to flower bud differentiation; and high levels ratio of m(ABA)to m(IAA)and m(ZT)to m(IAA)were beneficial to stamen development. 【Conclusion】 The abortion of the other sexual organ lead to the formation of female and male flowers in X.anthoceras sorbifolium. The internal differentiation period can be judged based on the external morphology during the flower bud differentiation. High levels of the ZT, m(ABA)/m(IAA), m(ABA)/m(GA), and m(ZT)/m(GA)are beneficial for flower bud differentiation. High levels of the ZT, IAA and ABA are beneficial for female flower development, and high levels of the GA, the ratios of m(ABA)to m(IAA)and m(ZT)to m(IAA)are beneficial for male flower development.