The Study Of Sex Differentiation And Anther Development Of Cardiospermum Halicacabum

Unisexual flower plant is bisexual flowers ancestors evolved, according to its development process, it can be divided into two types:Do not undergo bisexual flowers stage and undergo bisexual flower stage. Pistil or stamen degradation of most bisexual flowers, undergo bisexual flowers, occurs in the early stages of flower development, but stamen degradation occurred in the late anther development in many plants of Sapindaceae, thus forming the phenotype of pistillate flower is bisexual flower, we also call this pistillate flower pseudo-bisexual flower. Researchers have been studied the process of unisexual flowers sexual differentiation, anther development of staminate flowers and pseudo-bisexual flowers of Sapindaceae plant, but those researches mostly focused on woody plants. So, in this thesis, using and morphological observation, improved Alexander staining, artificial Pollination, anther overall squash technique, semi-thin and ultra-thin sections, periodic acid and shiff's reaction and sudan black B staining we studied morphological characteristics in unisexual flower development, pollen viability, anther development, anthers metabolic characteristics of polysaccharides and lipids of Sapindaceae herbaceous Cardiospermum halicacabum. Then we discussed the differentiation process of staminate flower and pseudo-bisexual flower and reasons of male sterility in pseudo-bisexual flower, etc.(1) When the bud length is less than 1.10 mm (before microspore vacuolization), flowers of Cardiospermum halicacabun are bisexual flower; when the bud length is 1.20-1.30 mm (two-celled pollen stage), pistils of most bisexual flowers stop developing then become staminate flowers. At the same time, there are still a few of bisexual flowers with normal stamens and pistils, but, at anthesis, their anthers are indehiscence. So they could be called pseudo-bisexual flower (female flower).(2) Pollen viability assay indicates that:pollens of staminate flower contain a lot of nutrients and their pollen viability is high, up to 97.91%; most pollens of pseudo-bisexual flower contain few nutrients, so their pollen viability is low, Low as 17.12.(3) The anther development process is similar between staminate flower and pseudo-bisexual flower before two-celled pollen:each anther of Cardiospermum halicacabum has four pollen sacs and each consists of epidermis, endothecium, two middle layers and a secretory tapetum; the development of the anther wall is of basic type; the microspore tetrads are tetrahedral and pollen grains are shed at two-celled stage. Compared with staminate flower, after two-celled pollen, tapetum cells of pseudo-bisexual flower rapidly degrade; lip cells are present; secondary wall thickening is incomplete of endothecium, cell wall is not degrade of connective cells. At anthesis, these anthers are not dehiscent.(4) Before two-celled pollen, the distribution of lipids and polysaccharides is similar in both types of flowers:only connective, epidermis, endothecium, middle layer cells have starch granules. Compared with staminate flower, after two-celled pollen, there are a few of lipid droplets in tapetum cells of pseudo-bisexual flower. At anthesis, most pollen grains contain only small amounts of starch granules.In conclusion:at the early development of bisexual flower, pistils of most bisexual flowers stop developing then become staminate flowers; at anthesis, their anthers are indehiscence, so they could be called pseudo-bisexual flower (female flower). Reasons of indehiscence of pseudo-bisexual flower maybe the combined effect of rapid degradation of tapetum, thickened incomplete of endothecium, not degrade the connective cell wall. At the same time, the rapid degradation of tapetum maybe destroy the synthesis of lipid metabolic pathways, resulting in its pollen is less than adequate nutrients and degradation.