Cytohistological study on rice pollen formation and maturation, and damages caused by cool temperature

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1. Newly established microtechnics for light and fluorescence microscopy and cryo-scanning electron microscopy were used to observe the formation and maturation of rice pollen and the early pollen germinating processes on the stigma as well as examined the cool temperature damages on these developmental processes. 2. Changes in the red autofluorescence from chioroplast in anther wall tissue during early pollen mother stages, the increasing trends in yellow autofluorescence from microspore and pollen outer wall, exine and germ pore of the pollen were found. To estimate pollen viability, FDA staining procedure for esterase activity as well as iodine-potassium iodide reaction for starch grain fillings were adopted, respectively. Dehiscence of anther wall and pollen dispersion process were observed and by cool temperature treatment before heading stages were observed to affect abnormally to these processes. 3. Pollen stigma interaction was observed under light and fluorescence microscope and cryoscanning electron microscope. Cryo technique during preparation procedures was thought to be important to preserve mature pollen on the stigma surface. 4. In addition, cryo-cutting method was found to preserve the inner structures of cut-surface of anther tissues and pollen cells. The developmental processes of anther and pollens were re-estimated using semi-thin resin embedding method and this cryo-fracture procedures. 5. By cool temperature treatment during panicle forming stages, incomplete dehiscence of anther wall, immaturity and abnormality of pollens, reduction of active pollen on the stigma surfaces, and degeneration of young embryo were observed under light microscope. 6. The combined microtechnics is very efficient for analyzing pollen development and maturation as well as pollen-stigma Interaction. These obtained results are summarized and reported as a small report.