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Changes in Rb + and Ca 2+ influx in winter wheat roots before, during and after exposure to low temperature and short days
Author(s) -
Jensén Paul,
Erlandson Gunvor
Publication year - 1986
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1986.tb01916.x
Subject(s) - chemistry , acclimatization , winter wheat , zoology , 2,4 dinitrophenol , nutrient , biophysics , botany , biochemistry , biology , agronomy , organic chemistry
Influx of Rb + ( 86 Rb + ) and Ca 2+ ( 45 Ca 2+ ) 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 −4 M 2,4‐dinitrophenol (DNP) reduced Rb + influx to a low and constant level, indicating that metabolic influx was the dominant process. In contrast, Ca 2+ 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 Ca 2+ ( 45 Ca 2+ ) during the uptake experiment. With the metabolic uncoupler inhibiting such extrusion the Ca 2+ ( 45 Ca 2+ ) 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 + , Ca 2+ influx increased during cold treatment, which could again be explained as inhibition of re‐export. The presence of DNP reduced Ca 2+ 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 Ca 2+ 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 Ca 2+ influx always decreased during the second week of post‐cold treatment.