Effects of medium components on in vitro pollen germination and pollen tube growth of Picea wilsonii Mast.

The effects of sucrose,calcium(CaCl_2) and boron(H_3BO_3) on pollen germination and pollen tube growth of Picea wilsonii Mast.were investigated and then the optimal medium was determined.The results showed that pollen germination was strict to the concentration of sucrose in cultured medium and had a significant range effect.Immunochemical localization of acid pectin and methyl-esterified pectin in the walls of pollen tubes was investigated by using monoclonal antibody JIM5 and JIM7,and observed by means of confocal laser scanning microscopy(CLSM).Immunolabeling revealed that acidic pectin accumulated in the extreme tip region and esterified pectin was only located at basal sites in pollen tubes cultured in boron-deficient medium.Studying using Fluo-3/AM revealed that the boron-deficient treatment altered the cytoplasmic Ca~(2+) distribution pattern and Ca~(2+) gradient disappeared.The results imply that boron may function as a regulatory factor of pollen tube growth by affecting the activity of the corresponding enzymes,inducing the extensibility and thus the foundation of the cell wall,and destroying polarity growth-dependent Ca~(2+) gradient,which might also contribute to the regulation of pollen tube growth.