Extracellular Calmodulin On Cedar Pollen Germination And Pollen Tube Growth

The involvement of extracellular calmodulin (CaM) in pollen tube growth of Cedrus deodara (Roxb.) Loud., a coniferous tree, was investigated by using two membrane-impermeable CaM inhibitors, anti-CaM and W7-agarose. Pollen germination and tube growth were inhibited by anti-CaM in a dose-dependent manner, while the same amount of mouse natural serum had no effect on either process. Pollen germination and tube growth were also inhibited by the CaM antagonist W7-agarose. FTIR microspectroscopy analysis showed that a decrease in carboxylic acid and an increase in saturated ester and protein in the walls of anti-CaM, W7-agarose treated cells. When pollen grains were grown in the culture medium added with anti-CaM, tip-focused cytosolic calcium in pollen tube disappeared as loaded with Fluo~3/AM (a fluorescent Ca2+ indicator). In addition, the amount of the total protein expression was reduced and several special bands were disappeared after anti-CaM treatment. These results indicated that extracellular CaM plays a pivotal role in pollen germination and tube growth.