The Study About The Programmed Cell Death Of Endosperm During Caryopsis Developing In Wheat

Programmed cell death (PCD) is a kind of physiologic cell death which happens initiatively according to the special process in specific tissues and organs at a certain stage of growth and developing in organism. In this experiment wheat(Triticum Aestivum L.)cultivar Yang Wheat No.12 was used as material, and the PCD progress of endosperm during development and the endosperm enrichment were studied. The main results we got were as follows.(1) The wheat endosperm cells underwent nucleus deformation and chromatin condensation. And the phenomenon became more obvious as endosperm development proceeding. The endosperm nucleus deformation happened at the 7th day after flowering, and the deformation became more and more sever with increasing days after flowering. The nucleoplasm leaked out in later days of endosperm developing. It showed that the death of wheat endosperm had active factor.(2) The nucleus deformation was influenced by space and force. The amyloplasts could be embedded in nucleus during endosperm developing. The degree of nucleus deformation had relationship with position, that was ,the nucleus near aleurone layer had more sever deformation than inner endosperm cells and the nucleus deformation of dorsal portion in caryopsis was lighter than ventral endosperm.(3) The PCD of endosperm cells in wheat during development was a kind of special phenomenon. The endosperm deformation happened at early days. Even after nucleus disintegration, the endosperm cells continued enriching, and the reserves including starch and storage proteins were still synthesized and accumulated in the cells as normal. It was the date of cell death until the cell was filled with starch.(4) Small starch granule occurred at the 18th day of flowering, and distributed close to endosperm cell wall where there was more endoplasmic reticulum, so that we conjectured that it had relationship between endoplasmic reticulum and small starch granules occurrence. We also found that small starch granules seems to have the indication of it's proliferation.