IDENTIFICATION OF HYPERPOLARIZATION-ACTIVATED CALCIUM CHANNELS IN THE APICES OF PYRUS PYRIFOLIA POLLEN TUBES
Pollen tubes haves been widely used to elucidate the mechanism underlying polarized tip growth. A steep tip-to-base cytosolic free calcium ([Ca2+]c) gradient is essential for growth of pollen tubes. Local Ca2+ influx, mediated by a Ca2+-permeable channel, plays an important role in maintaining the Ca2+ gradient. However, there has been no experimental evidence to demonstrate the existence of functional Ca2+-permeable channels in the plasma membranes of pollen tubes. In the present study, we developed a protocol to successfully isolate protoplasts successfully from pollen tubes of Pyrus portfolio, and identified a hyperpolarization-activated cation channel. The cation channel displayed a strong selectivity for divalent cations with a relative permeability sequence of Ba2+ ≈ Ca2+ > Mg2+ > Sr2+ > Mn2+. The Ca2+ conductance was inhibited by Ca2+ channel blockers (La3+ and Gd3+) and strongly dependent upon the extracellular Ca2+ concentrations.
Hai-yong Qu, , Lian-Mei Liu, and Shao-ling Zhang, (2008). IDENTIFICATION OF HYPERPOLARIZATION-ACTIVATED CALCIUM CHANNELS IN THE APICES OF PYRUS PYRIFOLIA POLLEN TUBES. Acta Hortic. 774, 95-104
Ca2+-permeable channels, patch clamp, pollen tube protoplasts, Pyrus pyrifolia