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.

XXVII International Horticultural Congress – IHC2006: International Symposium on Endogenous and Exogenous Plant Bioregulators

Hai-yong Qu, Lian-Mei Liu, Shao-ling Zhang

Ca²⁺-permeable channels, patch clamp, pollen tube protoplasts, Pyrus pyrifolia

https://doi.org/10.17660/ActaHortic.2008.774.11