Effects of Calcium Ion and the Protective Action on Survival and Growth Inhihition of Pollen

Abstract

Studies were condvicled on the protective action of Ca against growth inhibition and death of pollen from Crinum auaticum and Catharanthus TOSCUS. Ca ions not only promoted pollen germination and pollen tube growth, but also were antagonistic to pollen injuries induced by various chemical and physical treatments. Most of the chemicals used seemed to act as osmotic inhibitors, .f^mong the chemical agents tested, DNP inhibited pollen germination more strikingly with Ca than without it, whereas pollen tube growth was enhanced, .\nother metabolic inhibitor, low temperature, showed a similar effect on pollen germination. Insignificant or no protective action of Ca was observed when IAA, TIBA and coumarin, were applied.Large populations of pollen when grown in cultural media witbout Ca showed a partial protective action.The protective action of Ca in pollen growth against various inhibitors required other cations such as Mg and K ions. The promoting of pollen growth by Ca also required tbese otber cations.Tbe protective action of Ca is considered to be based on its binding in tbe pollen cell walls, particularly in the pectic regions. This gives rise to a decreased permeability and increased structural rigidity against tbe chemical and physical inhibitors.

Studies on Cellular Site of Calcium Action in Promoting Pollen Growth

“…Perhaps negatively charged groups in the pectin of the pollen cell walls heconie linked through Ca ions to compose a more strongly and effectively united colloidal system. The Ca action in pollen growth appears to increase the rigidity of the pollen cell walls and protect them against bursting (plasmoptysis), and al.so to regulate Ihe permeability of the walls which results in regulated uptake of solutes (15).…”

“…The findings Ihat Ca ions promote pollen fjei-miiialion and tube growth driimaticaily (3, 11, 15, 1(>), have led to fmlher investigations ol' tbe mode of Ca action at Ihe cellular level. Ca ions have also heen shown to induce the mutual stimulafion effect (3) and to protect pollen cells from various chemical and physical iiihibilors (11,15), when pollen was cuUured in vitro.…”