Premium
Influx and efflux of K + in sunflower roots after transfer between solutions with different K + concentrations
Author(s) -
Pettersson Sune,
KasimirKlemedtsson Åsa
Publication year - 1990
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.1399-3054.1990.tb00045.x
Subject(s) - efflux , sunflower , helianthus annuus , chemistry , dinitrophenol , analytical chemistry (journal) , nuclear chemistry , horticulture , chromatography , biology , biochemistry
It was investigated whether K + efflux, like K + influx, is affected when roots are transferred between solutions with different K + concentrations. Sunflower plants ( Hehanthus annuus L. cv. Uniflorus) were grown on complete nutrient solutions with 0.1, 1.0, 10 or 25 m M K + . This produced plants with K + concentrations in the roots varying between 9 and 110 μmol (g fresh weight) –1 . At the beginning of the experiments the plants were transferred to an 86 Rb‐labelled experimental solution initially containing 0.1 m M K + . At intervals during 6.5 h samples were removed from the solution and analyzed for K + and radioactivity. Based on the analyses K + ( 86 Rb) influx, K + net uptake and K + efflux could be computed. In‘low K + ’roots, K + ( 86 Rb) influx and K + net uptake agreed, suggesting a very low K + efflux. This was contrary to‘high K + ’roots, where K + efflux was initially higher than K + ( 86 Rb) influx. After about 4 h, K + efflux declined to a low value also in these roots. When 2‐4‐dinitrophenol was included in the experimental solution, K + ( 86 Rb) influx was generally depressed, whereas K + efflux was high throughout the experiment and directly proportional to the K + status of the roots. Our hypothesis is that after transfer of‘high K + ’roots to a solution with low K + concentration, the K + efflux from the vacuoles of root cells transiently increases, until a new electrochemical equilibrium is attained.