Pollen Grain Germination and Pollen Tube Growth of Chinese Giant Lily by SEM, EDAX and CTC Fluorescence

Abstract

Pollen grain germination and pollen tube growth of Chinese giant lily (Cardiocrinum giganteum) have been investigated as follows: scanning electron microscopy (SEM) morphology of pollen germination in vivo, and calcium distribution in germinating pollen grains and growing pollen tubes in vitro with energy-dispersive X-ray analysis (EDAX) and chlorotetracycline (CTC) fluorescence. Research materials were mainly collected from the plants wild-grown at Mount Emei in Sichuan. Self- and cross-pollination was made by hand in the open, and pollen grains collected were germinated in vitro as discribed commonly. Samples were withdrawn at the required intervals and prepared for SEM, EDAX and CTC fluorescence. SEM observation revealed that pollen grains start to germinate on stigmas 30 min after pollination, and there are linked secretions between germinating grains and between pollen and stigma as well as secretion granules on the exine surfaces and at the germinal furrows. For EDAX, measured along the pollen tube axis from the tip to the base, the tubes show a maximum of calcium concentrition at the tip region. Behind the region of about 5-10 um from the apex, the calcium concentritions fall remarkably and remain relative constant in the rest of the tube, The germinating grains show higher calcium amounts at the exine surfaces, especially at the germinal furrow region having a lot of calcium- rich bodies.