Kinetics of net H+, Ca2+, K+, Na+, NH+4, and Cl- fluxes associated with post-chilling recovery of plasma membrane transporters in Zea mays leaf and root tissues.

Abstract

Although temperature-induced changes in membrane structure and activity seem to be central to chilling stress perception, the specific details of temperature effects on plant nutrient acquisition remain obscure. In this study, we have undertaken a comparative study of low temperature effects on the activity of plasma membrane transporters of different ions in corn (Zea mays L.) leaf and root tissues by non-invasive measurements of net ion fluxes using ion-selective microelectrode (the MIFE) technique. Kinetics of net H+, Ca2+, K+, Na+, NH+4 and Cl- fluxes were measured as plant tissues recovered after short-term (3 h) chilling stress. The major findings can be summarized as follows: (1) The critical temperatures, under which the recovery of the activity of plasma membrane transporters took place, were found to be the same for all ions measured and are likely to be associated with the phase transition of membrane lipids. (2) The most pronounced was the reduction in net uptake of K+ and NH+4 (3) Chilling treatment caused a significant net influx of Cl- and Na+ in the leaf tissue. (4) For the same species, the critical temperatures for membrane-transport processes in roots were 2-2.5 degrees C lower than in leaves. Possible physiological significance of these findings is discussed.