Study On Endosperm Cellularization In Rice And Wheat

The endosperm cellularization is the important stage of the endosperm dvelopment. The formation of the initial cell wall contains anticlinal and percilinal cell wall and the process of the cell wall enrich were studied by resin embedding combined with semi-thin section technology and ultra-thin section technology. The main results were shown as follows:(1)There are two ways of the endosperm nuclear division: mitosis and amitosis, the mitosis is the main way of the division.(2)The cellularization of the endosperm is initiated in the vicinity of the peripheral embryo sac and proceeds to the inner embryo sac where it remains syncytial until well after the remainder of the endosperm has cellularized.(3) The cellularization occurs as waves originating in the micropylar chamber and moving through the central chamber toward the chalazal tip.(4) Prior to cellularization,the cytoplasm becomes more vacuolate:a mass of little vesicles surround the free nucleus, then the little vesicles fuse into larger vesicles. This is followed by initial anticlinal cell wall deposition between the adjacent endosperm nucleus.(5)The origin of the initial anticlinal cell wall come from the fusion of the phragmoplasts and the inward prominency of the embryo sac wall, while the initial percilinal cell wall come from the phragmoplas resulting in the alveoli periclinal division.(6)The free growing initial anticlinal cell wall shows expanse and a swollen distal tip. Vesicles around the dilated apex move to the expanse and a swollen distal tip with the help of the microtube, then these vesicles fuse with the dilated tip leading the initial anticlinal cell wall precede centripetally.(7)In the cytoplasm of rice, we found a kind of big vacuoles, which contain numbers of small vesicles, we named it"cell wall formation vesicle". This vesicle come from the cytoplasm and move to the newly cell wall, when it fuses with the cell membrane it may release the small vesicles to the cell wall.