Reactions of corn root tissue to calcium
Washing corn (Zea mays L.) root tissue in water causes loss of about one-third of the exchangeable Ca/sup 2 +/ over the first 10 to 15 minutes. Upon transfer to K/sup +/-containing solutions, the tissue shows a short period of rapid K/sup +/ influx which subsequently declines. Addition of 0.1 millimolar Ca/sup 2 +/ decreases the initial rapid K/sup +/ influx, but increases the sustained rate of K/sup +/ and Cl/sup -/ uptake. It was confirmed that 0.1 millimolar Ca/sup 2 +/ is more effective than higher concentrations for the initial inhibition, and that Mg/sup 2 +/ will substitute. The inhibition arises from a mild shock affect of restoring Ca/sup 2 +/. With 0.1 millimolar Ca/sup 2 +/ net H/sup +/ efflux is blocked for 10 to 15 minutes and the cells are depolarized by about 30 millivolts. However, 1 millimolar Ca/sup 2 +/ rapidly produces increased K/sup +/ influx and blocks net H/sup +/ efflux for only a few minutes; blockage is preceded by a brief net H/sup +/ influx which may restore and increase ion transport by reactivating the plasmalemma H/sup +/-ATPase. Stimulation of electrogenic H/sup +/-pumping with fusicoccin eliminates the shock responses and minimizes Ca/sup 2 +/ effects on K/sup +/ influx. Fusicoccin also strongly decreases Ca/sup 2 +/ influx, but has no effect on Ca/sup 2 +/ efflux. Ice temperatures and high pH decreased Ca/sup 2 +/ efflux, but uncoupler and chlorpromazine did not. It is suggested that the inhibitory and promotive actions of Ca/sup 2 +/ are manifested through decreases or increases in the protonmotive force. 29 references, 11 figures, 1 table.
- Research Organization:
- Univ. of Illinois, Urbana
- DOE Contract Number:
- AC02-76EV00790
- OSTI ID:
- 5004563
- Journal Information:
- Plant Physiol. (Engl. Transl.); (United States), Vol. 76
- Country of Publication:
- United States
- Language:
- English
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ATP-ASE
ENZYME ACTIVITY
CALCIUM COMPOUNDS
BIOLOGICAL EFFECTS
MEMBRANE TRANSPORT
HYDROGEN IONS 1 PLUS
POTASSIUM COMPOUNDS
UPTAKE
CATIONS
ELECTROPHYSIOLOGY
MAIZE
PLANT TISSUES
ROOTS
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BODY
CEREALS
CHARGED PARTICLES
ENZYMES
GRASS
HYDROGEN IONS
HYDROLASES
IONS
PHOSPHOHYDROLASES
PHYSIOLOGY
PLANTS
TISSUES
560303* - Chemicals Metabolism & Toxicology- Plants- (-1987)