RESUMEN
The effects of the cholera toxin (CTX) and pertussis toxin (PTX), which can activate and antagonize respectively the heterotrimeric G protein, on pollen germination, pollen tube growth and the dynamic of cytosolic free calcium concentration ([Ca(2+)]i) in pear pollen were investigated using Laser Confocal Scanning Microscope (LCSM). The results show that CTX could stimulate pollen germination and tube growth while PTX had the opposite effect. CTX and PTX had marked influence on the dynamic of pollen [Ca(2+)]i. The CTX treatment had no significant effect on the changes in pollen [Ca(2+)]i during pollen germination, but induced specific signaling of "calcium transient" in pollen. Treatment with PTX caused decline of pollen [Ca(2+)]i in the first 18 min after treatment. These data suggested that the regulation of pollen germination and tube growth in Pyrus serotina may involve in heterotrimeric G protein, which can stimulate specific change of pollen [Ca(2+)]i.