肌醇磷脂信号途径参与胞外钙调素启动花粉萌发和花粉管伸长

高等植物有性生殖是植物发育生物学研究的重要内容之一，而作为雄配子体的花粉在雌蕊柱头上萌发及花粉管在花柱内的持续生长是有性生殖实现的关键。已有许多研究表明Ca2 在花粉萌发和花粉管生长过程中起重要作用。最近，我室在多年细胞外钙调素（calinodulin，CaM）存在。性质及生物学功能研究（孙大业等1995；Sun等1994，1995；Tang等1996）的基础上，通过不过膜的大分子CaM拈抗剂或抗体并结合恢复实验证实细胞外CaM对花粉的萌发和花粉管的伸长具有启动作用（马力耕和孙大业1996），并发现G蛋白、质膜Caz”通道及胞内依赖Caz”的蛋白…

The Involvement of Phosphoinositide Signaling Pathway in the Initiatiory Effects of Extracellular Calmodulin on Pollen Germination and Tube Growth

In our previous reports, wehave verified the involvement of G protein, Ca2 channel in plasma memband CDPK in extracellular calmodulin(CaM) signal transduction chain for theinitiatory effects of extracellular CaM onpollen germination and pollen tubegrowth . In this paper, both normal andexogenous CaM-enhanced pollen germination and tube growth were completelyinhibited by the phospholipase C inhibitor U-73122 (Fig. 1 ). The enhancement of pollen germination and tubegrowth by the G protein agonist choleratoxin were also completely inhibited byU-73122 (Fig. 2), whereas the inhibition of pollen germination and tubegrowth by the G protein antagonist pertussis toxin was reversed by IP3 (Fig. 2).Heparin, an antagonist Of IP3 receptor,inhibited pollen germination and tubegrowth (Fig. 3 ), while thapsigargin increased cytosolic Ca2 by inhibiting theIP3-specific Ca2 pump in endoplasmicreticulum, and thereby increased pollengermination and tube growth (Fig. 4).The above results suggest that phosphoinositide signaling pathway might be involved in the extracellular CaM signaltransduction chain in the initiatory effectsof extracellular CaM on pollen germination and tube growth.