关键词: 花粉萌发, 花粉管生长, 钙, 钙通道阻塞剂, 钙载离子体

Abstract: The initiating effects of Ca²⁺ on pollen germination and its regulative role in pollen tube growth were investigated in Pinus yunnanensis and Nicotiana tabacum. High concentration of Ca²⁺(10^-1 ～10^-2mol/L) in the medium caused severe inhibition of pollen germination and tube growth, but lower concentration of Ca²⁺ or Ca²⁺-deficiency(10^-3 ～ 0 mol/L)had little effect onpollen germination and tube growth. Measurement of Ca content ingerminating pollen showed that there was a significant Ca²⁺ release from pollen during the hydration and early germination phase. However, Ca²⁺ specific chelating agent EGTA led to the inhibition of pollen germination, and this inhibition could be eliminated by re-adding excess Ca²⁺ to the medium containing EGTA. Ca²⁺ channel blockers verapamil and Co₂₊ also caused the inhibition or failure of pollen germination. In addition, Ca²⁺ ionophore A₂₃₁₈₇impeded pollen germination and tube growth. Unlike verapamil and Co₂₊ treatments, pollen tube growth was more sensitive to A₂₃₁₈₇ than pollen germination. These results suggested that Ca²⁺ is indispensible for pollen germination and tube growthalthough exogenous addition of Ca²⁺ to the medium is not necessary. The uptake of Ca²⁺ occurred mainly in early germination phase, and Ca²⁺ could act as an initiator of pollen germination and also as a regulator of pollen tube growth.

Key words: pollen germination, pollen tube growth, Calcium, Ca²⁺ channel blockers, Ca²⁺ ionophore