Ultrastructural Study On Microsporogenesis And Development Of Male And Female Gametophytes In Senecio Cannabifolius Less.

In this paper,Transmission Electron Microscope was used to study the microsporogenesis and ultrastructural characteristics of male and female gametophyte development of Senecio cannabifolius Less.,which enriched the reproductive biological data and provided theoretical basis of the genetics and breeding of Senecio cannabifolius Less.The main research results are as follows:1.Each flower has 5 stamens,and each stamen has 4 anthers.During meiosis,microspore mother cells are surrounded by callose,and the cytoplasmic division is simultaneous type.There are four layers of anther wall,including epidermis,anther wall,middle layer and tapetum.The tapetum development type is deformation tapetum.2.Senecio cannabifolius Less,anatomic photon cell,basal placenta,single locular,single ovule,anatropous ovule,parenchyma,integument tapetal.Megaspore mother cells formed linear tetrads through meiosis,and the chalazal megaspore developed into functional megaspore,and the embryo sac developed into polygonum type.3.In the process of meiosis,the cytoplasm of microspore mother cells was rich in organelles at the tene stage,and the number of organelles decreased in the early stage I,the mitochondrial crest decreased,and the plastid electron density was low.At metaphase I,the regular change of organelles was "cytoplasmic reorganization".At the late stage,I did not form a cell plate,but formed an obvious "organelle band",which separated the two daughter nuclei.At the diad stage,the "organelle band" still existed,with abundant organelles inside.4.Anther more developed at the early stage of the microspore mother cells,the deformation of tapetum single or two nuclei,pull over to the mononuclear period when plasma group began to indoor mobile,to collapse during the period of two cells,form in drug indoor electronic transparency high plasma,to the period of mature pollen outside the pollen wall is still visible less protoplast;The middle layer developed in meiosis stage,reduced cytoplasm and flattened cells in mononuclear microspore stage,and degenerated in mononuclear sidelining stage.The cell structure of the chamber wall was abundant during meiosis,and the cytoplasm decreased to monocyte microspore stage and increased to two-cell stage.Epidermal cells have little cytoplasm in the first division of meiosis,little cytoplasm in the diad stage,and then vacuoles occupy the cells.The inner wall of pollen wall begins to form in the tetrad stage,and the outer wall has initial outline in the mononuclear microspore stage.The outer wall has formed in the mononuclear marginal stage,and the pollen wall becomes mature in the two-cell stage,and the pollen wall appears flower cluster aperture in the mature pollen stage.5.Mononuclear embryo sac after mitosis to form three times eight nuclear embryo sac,eight nuclear free in which both are located in the pearl Kong Duan "inverted U" type,eight nuclear embryo sac formed by the cells after a mature embryo sac,mature embryo sac bead Kong Duan egg nuclei two synergid,chalaza end with 5 ? 7 antipodal cells,the cells located in the pearl Kong Duan with the conjunction between secondary nucleus is located in the pearl Kong Duan,Half of the volume of the embryo sac is occupied by the large central vacuole.With the development of the flower bud,the synergid begins to degenerate,and the degeneration time of the two synergid is different successively.After the degeneration of the degraded synergid,mitochondria and other organelles can also be seen in the cytoplasm of the persistent synergid.6.When the flower bud just opened(before pollination),the antipodal cells degenerated,and the zymote end of the embryo sac turned into a rod-like structure.At this time,there were no egg cells and the central cell at the microphylla end,and the egg cell was in the shape of a yangyang pear.The nucleus of the central cell lies in the middle,surrounded by cytoplasm,and there is no large central vacuole.7.From the stage of megaspore mother cell to mononuclear embryo sac,megaspore mother cell was enveloped by nucellus epidermis,and degenerated from mononuclear embryo sac to tetrakaryocyst.The integual tapetal layer is closely arranged and close to the embryo sac from the stage of tetrapyclic embryo sac to the stage of mature embryo sac,and is most developed before the degeneration of synergid.When the degeneration of antipodal cells,the radial elongation becomes ellipsoid,and the cell volume becomes significantly smaller,but the cytoplasm still contains mitochondria,plastids and other organelles.8.The intramural process is a special structure for the embryo sac to absorb nutrients.The megaspore mother cell begins to have intramural process in the dyad stage,and there are high electron density materials in the intramural process in the tetrapyclic embryo sac stage,and organelles in the octagyclic embryo sac stage.9.The pollen of qianli light of Hemp leaf has the phenomenon of shrinkage,only the material with deep electron density inside the cell can not identify the cell structure,which is the phenomenon of pollen abortion.The phenomenon of embryo sac abortion is that the embryo sac has cavity and floccule substance without cell structure.