Cytobiology Observation Of The Pistils' Selectivity Abortion In Male Flower Of Xanthoceras Sorbifolia Bunge

Xanthoceras sorbifolia Bunge.,a typical woody oleiferous plants and the important biomass energy plants,has a strong drought and cold resistance as afforestation pioneer in the North of China. Xanthoceras sorbifolia Bunge.is andromonoecious with staminate flower and hermaphrodite flower growing in one plant.It's stamens in staminate flower develop in normal,but the pistils happen selectivity abortion during the sex determination.In order to completely understand the period, structural feature and mechanism of the pistillate organ's selectivity abortion of staminate flower during the sex determination.In this paper,based on the original investigation,the processes of selectivity abortion and normal development were observed serially from cell morphology and histochemistry,by choicing two homochronous kinds of pistil tissue as research materials,which are respectively the selectivity aborting pistil tissue of staminate flower and the normal developing pistil tissue of hermaphrodite flower of the Xanthoceras sorbifolia Bunge.The period of the pistil selectivity abortion was found out.And the mechanism of the pistillate organ selectivity abortion of staminate flower during the sex determination was discussed.These offer not only morphological evidence but also the theory base for research of abortion related proteins and genes of female selectivity abortion.First of all,at the level of tissue and cell,the selectivity aborting pistil tissue of staminate flower and the normal developing pistil tissue of hermaphrodite flower were comparative studied by measuring and the paraffin-cross section method.The result revealed that the pistils' abortion began from the diplotene stage of meiosis I of megaspore mother cell.Besides,parenchyma cells at the placenta region,carpel septum and the ovary wall also occur vacuolation at different levels with pistil abortion taking place,and the structural of ovule breaks down..At the same time,histochemical techniques were also used to observe the starch grains and proteins in pistil accumulated in the processes of selectivity abortion of staminate and normal development of hermaphrodite flower,The result revealed that there isn't the starch grains and proteins decrease slowly with the abortion taking place,presuming that the lack of nutrition maybe one of the causese of pistil abortion,as well as providing the base for abortion related proteins' study.After the period of the pistil abortion were observed,the structure and relationship with programmed cell death of aborted cells were researched at subcellular level using electron microscope technique.From the result,in abortive cells in the eve of the selectivity abortion and the stage of abortiong,there is phenomenon of nucleolus disintegrating and chromatic agglutination and marginalization,belong to the typical PCD.Various kinds of organelles,involving vacuole and mitochondrion,and kinds of membrane structures also breakdown,resulting in ovule abortion.In addition,it's observed that cell walls of abortive ovule thicken partly and abnormally with undeveloped plasmodesmata in the eve of the pistil selectivity abortion,that may hinders intercellular nutrient transport and information transfer.