Megasporogenesis,Microsporogenesis and Development of Gametophytes in the Rare Endangered Plant Manglietia patungensis Hu

A detailed morphological description of megasporogenesis,microsporogenesis,and development of the male and female gametophytes in the rare endangered plant Manglietia patungensis Hu is presented for the first time after three-year’s continuous investigation.The ovule is anatropous,bitegmic,crassinucellate and with a obturator.No irregularities have been found in the process from the differentiation of archesporial cells to the formation of megaspores.The megaspore mother cells undergo miosis and develop into a linear tetrad.The large one at chalazal end is functional megaspore and developed into a polygonum type of embryo sac after the third mitotic division.Each anther of M.patungensis Hu with four sacs,a mature anther wall successively comprises an epidermis,endothecium,two-layered middle layer and one or two-layered glandular tapetum.The meioses of microspore mother cell is normal and cytokinesis is modified simultaneous type,and tetrads are tetrahedral,decussate and isoblateral,occassionally linear.The pollen grains are monocolpate and two-celled at shedding and the pollen grains germination rate is more than 90%.These results indicate that the key factors for the low seeding rate do not involved the development process of male and female gametophytes.