Issue Archive

A novel cation channel in Vicia faba guard-cell plasma membrane

Wu Weihua

Department of Plant Physiology and Biochemistry, College of Biological Sciences. Beijing Agricultural University. Beijing 100094

Abstract

Patch clamp technique was used to study K+ channels in Vicia faba guard-cell plasma membrane. Novel cation channels with high conductance were observed and recorded at both whole-cell and single-channel levels in some guard cell protoplasts. The channels were identified as K+ channels at whole-cell level by the reversal potential of tail currents. Whole-cell inward K+ currents at -180mV were between 1.5 and 2.5nA per cell in those guard-cell protoplasts with high membrane conductance, while inward K+ currents at -180mV were only 0.3-0.5nA per cell in most of the calmped guard-cell protoplasts used for experiments. The normalized whole-cell inward K+ currents (pA/pF) at -180 mV were 0.3 to 0.3nA per cell for those guard cells was 5 to 8 times higher than that from the most of guard cells. Single-channel recordings in some membranc patches also showed cation channel activity with unusually high conductance. Single channel conductance of these novel cation channels was approximately 5 times of that of the normal K+ channels in most membrane patches and of the previously repored inward K+ channels in the plasma membrane of Vicia faba guard cells. It is concluded that there are cation channels with high conductance in some guared guard cells, which may provide physiological mechanisms for rapid response of stomata to environmental stresses.

Key words: Vicia faba;Stomata;Guard cell;Plasma membrane;K~(+) channel;Patch clamp

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Wu Weihua. A novel cation channel in Vicia faba guard-cell plasma membrane. Acta Physiol Sin 1995; 47 (4): (in Chinese with English abstract).