Effects of environmental factors on nonselective cation channels-mediated potassium uptake of wheat roots

The nonselective cation channels(NSCCs)in plant roots contribute to the potassium transport across cell membrane. However, the ratioa of NSCCs-mediated K+ uptake to total K+ absorption by crops, and whether this process is affected by the environmental factors are still unknown. In this paper, the wheat cultivar Shijiazhuang 8 was used as material to study the effects of temperature and heavy metals(cadmium and copper)on K+ transport by NSCCs. The results show that the optimum temperature for NSCCs K+ uptake is about 35℃, and lower or higher temperature reduces the rate of K+ uptake by NSCCs. NSCCs-mediated K+ uptake is more sensitive to higher temperature(40℃)compared with the specific K+ channels, while NSCCs-mediated K+ uptake is more tolerant to lower temperature(20℃). The effects of cadmium and copper on NSCCs-mediated K+ uptake are dependent on their concentrations. Compared with the specific K+ channels, NSCCs are less sensitive to Cd2+ and more sensitive to Cu2+, which indicates that different heavy metals may influence the two types of channel proteins in different ways.