ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Influx of Rb+(86Rb+) and Ca2+ (45Ca2+) in roots of intact winter wheat (Triticum aestivum L. cv. Weibulls Starke II) was determined at intervals before, during and after exposure to cold acclimation conditions (2°C and 8 h light period). The plants were grown in nutrient medium of two ionic strengths. During the initial two weeks of growth at 16°C and 16 h light period, Rb+ influx into roots decreased with increasing age, probably as a consequence of a decreasing proportion of metabolically active roots. The presence of 10−4M 2,4-dinitrophenol (DNP) reduced Rb+ influx to a low and constant level, indicating that metabolic influx was the dominant process. In contrast, Ca2+ influx in plants grown in full strength nutrient solution was higher in the presence than in the absence of DNP. This effect may have been due to an active extrusion mechanism mediating re-export of absorbed Ca2+(45Ca2+) during the uptake experiment. With the metabolic uncoupler inhibiting such extrusion the Ca2+(45Ca2+) influx mesured would increase. During cold treatment, Rb+ influx remained at a low level, and was further decreased when DNP was present in the uptake solution. This effect may have been due to inhibition of residual active influx of Rb+ at 2°C by the uncoupler and/or to a decrease in membrane permeability. In contrast to Rb+, Ca2+ influx increased during cold treatment, which could again be explained as inhibition of re-export. The presence of DNP reduced Ca2+ influx at 2°C, indicating decreased membrane permeability by DNP at low temperature. After transfer of plants from cold acclimation conditions to 16°C, Rb+ and Ca2+ influx increased in plants grown at both ionic strengths. Influx levels were independent of the length of the cold acclimation period (1, 6 and 8 weeks), but the patterns were different for the two ions. After each of the cold acclimation periods, Rb+ influx increased during the first week and decreased or remained at the same level during the second week, while Ca2+ influx always decreased during the second week of post-cold treatment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1986.tb01916.x
