Study On Calyx Morphology Anatomy And Sporogenesis Development Of Physalis Alkekengi

Physalis alkekengi L. is a kind of herbaceous perennial plant in the Solanaceae family, mainly to wild,the precious plant resources with a variety of functions such as ornamental, edible and medicinal values,and also has broad prospects for development and application. It has attracted widespread attention due tothe novel structure of persistent and swelling calyx. In this paper, morphological observation has beenconducted on calyx of Physalis alkekengi in different developmental stages. And we also further studiedtheir structure combined with anatomy (semi-thin sections and scanning electron microscopy). Meanwhile,we have researched embryology of Physalis alkekengi by paraffin section technology, thus exploring thecorrelation between the development of the flower buds and that process of pistil and stamen. Sum up theabove findings, conclusions are following:（1）From morphological observation: Early calyx sepals of Physalis alkekengi tightly coated buds.With the opening of the flower, calyx also continued to grow, the tip of the calyx started to expand slowlyuntil calyx lobes fully expanded, buds fully swelled. And then the size of calyx did not change until theflowers withered away. Instead of falling off, with the growth and development of fruit, calyx continued togrow. Especially, the base expanded rapidly. And the top calyx closed slowly to coat fruit. When the size offruit no longer increased, calyx stopped growing and the size also tended to be stable. In this process, thecolor of calyx changed gradually from dark green to red. In the flowering, calyx surface had a lot of fluff.But later, it became smooth and hairless.（2）From anatomical studies: Using the semi thin section technology, we did crosscutting with calyxof Physalis alkekengi in different developmental stages and selected six representative developmentalstages of calyx as research and analysis objects. We found that sepals consist of epidermis, mesophyll andvascular bundles, similar to the blade structure. In the outer wall of epidermal cells, cuticle thickens of theconstantly along with calyx development. Mesophyll consists of parenchyma cells which have big andobvious vacuoles and also contain a large number of chloroplasts in the Green calyx; as the calyx develops,parenchyma cells constantly elongate, intercellular spaces increasing. Vascular bundle is bicollateral,almost rounded. Using scanning electron microscopy, we scanned Physalis alkekengi calyx epidermis in different developmental stages just the same as that when using the semi thin section technology and foundthat the Physalis alkekengi calyx outer epidermis has non-glandular hairs and pores, and inner epidermisonly has glandular hairs. Later, both glandular and non-glandular hairs fall off. Initial stage, outer epidermalcells are small and closer without obvious boundary, surface of which are relatively flat. With the growth ofcalyx, the size of outer epidermal cells increases gradually with the outer wall bulging outward and obviousboundary. In regard to inner epidermal cells, they have more obvious boundary and greater changes indifferent stages. By comparison to structural characteristics and the number of cells in differentdevelopmental stages of Physalis alkekengi calyx, we can find that calyx enlargement is just the result ofelongation growth of cells rather than increase in the number of cells.（3）Development of Physalis alkekengi stamen: The anther wall is constituted by endothecium,middle, and glandular tapetum together with the epidermis. Archesporial cells first develop into the primarysporogenous cells, and then, by cellular cleavage, form secondary sporogenous cells, which functiondirectly as microspore mother cells. Microspore mother cells undergo meiosis through simultaneouscytokinesis and give rise to tetrads of microspores, which are tetrahedrally arranged and surrounded bycallose wall. Finally, due to the dissolution of callose wall, four small spores are separated from each otherto form a single microspore. After a split, microspores develop into two-cell mature pollen grainscontaining germ cell and vegetative cells.（4）Development of Physalis alkekengi pistil: Development of ovule primordia forms archesporialcell. Archesporial cell grows directly into megaspore mother cell which forms a linear megaspore tetrad bymeiosis. At the micropylar end, three megaspore program to die naturally; at the chalazal end, only amegaspore continue to develop into functional megaspore, then into the embryo sac mother cell which, bymitosis, gradually forms two nuclear embryo sac, four nuclear embryo sac, eight-nucleate embryo sac, andeventually form mature embryo sac of an egg, two synergids, two polar nucleus and three antipodal cells.Development of embryo sac is polygonum type.（5）Development of pistil and stamen of Physalis alkekengi has a certain relevance with themorphological changes of flower buds. Developmental stages of pistil and stamen can be determined byobserving the buds form of Physalis alkekengi, which will provide some theoretical basis for Physalisalkekengi breeding research.