ISHS Acta Horticulturae 774: XXVII International Horticultural Congress - IHC2006: International Symposium on Endogenous and Exogenous Plant Bioregulators
IDENTIFICATION OF HYPERPOLARIZATION-ACTIVATED CALCIUM CHANNELS IN THE APICES OF PYRUS PYRIFOLIA POLLEN TUBES |
| Authors: | Hai-yong Qu, Lian-Mei Liu, Shao-ling Zhang |
| Keywords: | Ca2+-permeable channels, patch clamp, pollen tube protoplasts, Pyrus pyrifolia |
| Abstract:
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. | |
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