Reale Lara, Sgromo Carlo, Ederli Luisa, Pasqualini Stefania, Orlandi Fabio, Fornaciari Marco, Ferranti Francesco, Romano Bruno
Department of Applied Biology, University of Perugia, Perugia, Italy.
Sex Plant Reprod. 2009 Sep;22(3):109-19. doi: 10.1007/s00497-009-0096-1. Epub 2009 Apr 2.
In olive (Olea europaea L.), the formation of functionally staminate flowers rather than fully functional hermaphrodites is one of the major factors limiting fruit set, as flowers with aborted pistils are incapable of producing fruit. Studies conducted on various angiosperm species have shown a correlation between flower abortion and starch content. Thus, it is important to know if starch content plays a role in regulating pistil development in olive and if so, what mechanism regulates starch distribution. Cyto-histological observations of staminate and hermaphrodite olive flowers show that pistil development in staminate flowers is interrupted after the differentiation of the megaspore mother cell. At that stage, starch grains were only detected in the ovary, style and stigma of the hermaphrodite flowers. No starch was observed in the pistils of the staminate flowers. This finding suggests a tight correlation between starch content and pistil development. The secondary origin of starch within the flower is indicated by low chlorophyll content in the gynoecium, undetectable Rubisco activity in the pistils of these two kinds of flowers and by the ultrastructure of the plastids observed by transmission electron microscope analysis. The plastids have few thylakoid membranes and grana and in the staminate flowers appeared very similar to proplastids. Considering differences in starch content between staminate and hermaphrodite flowers and the secondary origin of the starch, differences in pistil development in the staminate and hermaphrodite flowers could be related to differences in the sink strength of these two types of flowers.
在油橄榄（Olea europaea L.）中，形成功能上的雄花而非完全功能的两性花是限制坐果率的主要因素之一，因为雌蕊败育的花无法结果。对各种被子植物物种进行的研究表明，花败育与淀粉含量之间存在相关性。因此，了解淀粉含量是否在调节油橄榄雌蕊发育中起作用，如果是，什么机制调节淀粉分布很重要。对油橄榄雄花和两性花的细胞组织学观察表明，雄花中的雌蕊发育在大孢子母细胞分化后中断。在那个阶段，仅在两性花的子房、花柱和柱头中检测到淀粉粒。在雄花的雌蕊中未观察到淀粉。这一发现表明淀粉含量与雌蕊发育之间存在紧密的相关性。花内淀粉的次生来源通过雌蕊中低叶绿素含量、这两种花的雌蕊中未检测到的核酮糖-1,5-二磷酸羧化酶活性以及通过透射电子显微镜分析观察到的质体超微结构来表明。质体具有很少的类囊体膜和基粒，并且在雄花中看起来与原质体非常相似。考虑到雄花和两性花之间淀粉含量的差异以及淀粉的次生来源，雄花和两性花中雌蕊发育的差异可能与这两种花的库强度差异有关。
