The Distribution Features of Polysaccharides and Lipids in the Development of Tomato Anthers

The regulation of nutrient transportation and transformation in developing anthers is very complex. We analyzed the distribution and features of polysaccharides and lipids in the developing anthers of tomatoes using histochemical methods. Some starches appeared in the connective somatic tissue of anthers during the sporogenous cell stage. Before meiosis of the microspore mother cell,a thick polysaccharide callose wall was formed,accompanied by a reduction in the connective tissue starches. During the tetrad stage after meiosis,the polysaccharide material in the anther did not change. At the early microspore stage,the starches in the connective cells again increased,and polysaccharide material appeared in the partial intine of pollen. At the late microspore stage,a large vacuole formed that did not contain lipids or starches,and only the pollen wall contained red polysaccharides. At this stage,the connective somatic cell starch amounts decreased,and the tapetal cells changed shape and degenerated. After microspore division,abundant lipids appeared in the bicellular pollen,and starches accumulated following pollen development. As the anthers matured,many lipids and some starches accumulated in the epidermal cells. Nutrient metabolism within the tomato pollen characteristically accumulated lipids first and then starches,while the mature pollen accumulated starches and lipids simultaneously. This characteristic pattern of nutrient metabolism in tomato pollen shows species specificity among plants.

Embryological Studies on Narcissus tazetta var.chinensis

Chinese narcissus(Narcissus tazetta var.chinensis Roem)blooms but has no seeds.Embryological studies on the species were conducted to discover the causes of its sterility.Its anther wall is composed of four layers of cells,and its tapetum is of the secretory type.The cytokinesis of microspore mother cells is of the successive type,and the tetrad is tetrahedral.During meiosis of microspore mother cells,some chromosomes lagged,and several micronuclei were found in tetrads.Only 27.7%of the pollen grains contained full cytoplasm,and 1.3%of them germinated in culture medium.No pollen grain,however,could germinate on the stigma.The ovary is trilocular with axile placenta,and the ovules are bitegmic,tenuinucellate,and anatropous.Its embryo sac is of the polygonum type.Most embryo sacs degenerated,and only about 4.5%of the ovules contained a normal embryo sac with an egg cell,two synergids,three antipodal,and a central cell containing two polar nuclei.One reason for the sterility of Chinese narcissus is the abnormality of microsporogenesis and megasporogenesis,in which only a few functional pollen grains and embryo sacs are produced.The other reason is that the pollen grains cannot germinate on the stigma.