The reproductive biology theory of sporogenesis and gametogenesis in Polygonatum zanlanscianense Pamp.

Abstract

[ Objective ] In order to enrich the reproductive biology theory of Polygonatum Mill. and provide the basis for breeding of Polygonatum zanlanscianense Pamp. , the morphological structure characteris- tics , megasporogenesis and microsporogenesis , and the development process of male and female gameto- phytes of P . zanlanscianense were studied. [ Methods ] The flower buds of P . zanlanscianense at different developmental stages were used as experimental materials. The morphological and structural characteris- tics of the flowers were observed by microscopic observation , and the single flower pistil and stamen were observed by paraffin sectioning technique. [ Results ] The perianth of P . zanlanscianense was white or yel- lowish green , and the perianth tube was slightly constricted near the throat. It had 6 stamens , the lower end of filaments and anthers were united , and the anther was longitudinally split. The pistil ovary was su- perior , each ovary consisted of 3 carpels , and the style was equal to the ovary. The anther wall of P . zan- lanscianense was composed of 4 layers of cells. The mature tapetum had multiple nuclei , and the develop- ment type of tapetum was secretory. The meiotic division of microspore mother cells was continuous , tet- rads were arranged symmetrically , and mature pollen grains were 2-cell type. The microspore development was not synchronized. Pistil ovule had double integument and thick nucellum. The tetrad was linear and the embryo sac was of polygonum type. The phenomenon of double embryo sac ovule was observed. The calcium oxalate crystals were observed in the anther wall of the stamen and the ovary wall of the pistil. [ Conclusion ] The stamens and pistils of P . zanlanscianense have more primitive development characteris- tics. Although there are abnormal phenomena in the development process , the stamens can eventually form normal male gametophytes. The phenomenon of double embryo sacs with low frequency of pistils has little effect on the overall fertilization. The pollen before anther dehysis can be selected for cross breeding of P . zanlanscianense . The bundle-shaped calcium oxalate needles observed in anther wall and ovary wall cannot be used as the basis for species identification of P . zanlanscianense.

Keywords

• polygonatum zanlanscianense pamp.
• megasporogenesis and microsporogenesis
• male and fe- male gametophyte