Study On Embryology Of Prunus Mahaleb Linn

Prunus mahaleb Linn is a breeding resource plant of cherry imported from Hungary bycollege of horticulture of Northwest A&F University.It belongs to Rosaceae and has theexcellent biological characteristics such as the high resistance of crown gall disease,dwarfand early fruit,strong tolerance of saline-alkaline,it has became one of the main root stock ofsweet cherry in northwest.However,the embryology of Prunus mahaleb Linn has not beeninvestigated.In daily life,the seed setting rate of Prunus mahaleb Linn is low,in order to solvethis problem and to make better use of germplasm resources,we have to study the embryologyof Prunus mahaleb Linn.The results of this research can be summarized as follows:1.The flower bud morphological differentiation of Prunus mahaleb Linn generallystarted in the mid to late June, focused differentiation stage In July-August. Thedifferentiation process of the Prunus mahaleb Linn including bract primordium formation,Inflorescence primordium differentiation stage, sepal primordium differentiation stage, petalprimordium differentiation stage, stamen primordium differentiation stage and pistilprimordium differentiation stage and so on.2.The anther of Prunus mahaleb Linn has four chamber and its wall includes4layer， anther wall i ncludes the epidermis，fi brous layer，middle layer and tapetum.Theepidermis only has one layer and always exists.Middle layer and tapetum dispear graduallyduring the pollen development. The tapetum still in its location so it is galandulartapetum.When the anther wall is mature It only remains epidermis and fibrous layer. In themeiosis of microsporocyte， cytokinesis is simultaneous type.And microspore tetrads aretetrahedral.Mature pollen are3-celled.The mature pollen grains are observed using scanningelectronic microscope (SEM). There are three germinal furrows in the exine of pollen withhorizontal stripes and seems like a flat triangular.3.The ovary is1-loculus with2anatropous ovules in it.The ovule is bitegminous andcrassinucellate.Usually one archesporium functions directly as megaspore mothercell.Cytokinesis in the megaspore mother cell usually accompanies meiosis，and the chalazalMegaspore of a linear tetrad is functional one.The embryo sac is polygonum type.Mature embryo sac has7cells with8nucleus.4.The development of embryo belongs to aster type.The fertilized egg usually undergoarest period before embarking on its first division.After the club-shaped embryo， theglobular embryo，the heart-shaped embryo，and the fish-torpedo embryo develop to themature embryo. And the division of primary endosperm nucleus takes place before division ofthe zygote.The primary endosperm does not undergo the rest period,and immediatelymitosises.Endosperm is nuclear type.5. According to the experiment we find that the abortive of pistil primordia,microsporeand early development of embryo lead to the low seeding rate of Prunus mahaleb Linn.