Development and function of membrane systems in plant tissue. Final technical progress report, 1 February 1983-30 June 1984
A study of Ca/sup 2 +/ transport in and out of corn root cells has been conducted. Any type of shock or injury opens cell membranes to Ca/sup 2 +/ influx - cold, heat, acid, cutting, depolarization with cyanide, uncoupling with a protonophore. Freshly excised root tissue has a high Ca/sup 2 +/ permeability that is reduced after 1 hour of washing. Fusicoccin, which hyperpolarizes the cells retards Ca/sup 2 +/ influx in washed tissue but has no effect on freshly cut tissue. Calcium influx in all cases is strongly inhibited by La/sup 3 +/. Ca/sup 2 +/ transport was studied in isolated tonoplast and plasmalemma membrane vesicles. Both vesicles show calmodulin stimulated Ca/sup 2 +/-ATPase transport. However, only the tonoplast showed uncoupler-sensitive H/sup +//Ca/sup 2 +/ exchange transport and uncoupler-sensitive ATPase activity. Pretreatment of corn root tissue with 10 ..mu..M indoleacetic acid (IAA) for 10 min produced a plasmalemma fraction which did have uncoupler-sensitive Ca/sup 2 +//H/sup +/ exchange transport and ATPase activity. Also, the presence of 5 ..mu..M IAA retarded the K/sup +/ leakage which results from tissue excision. IAA acts to protect the plasmalemma from injury. The Ca/sup 2 +/-stimulated protein kinase which phosphorylates cell membranes was studied further. Protein phosphorylation strongly inhibits the H/sup +/-pumping ATPase. Calcium stimulates the phosphorylation of 8 proteins in the plasmalemma, 2 in the tonoplast. The protein responsible for control of the H/sup +/-ATPase has not been identified. Since Ca/sup 2 +/ influx is voltage controlled, we inquired whether Na/sup +/, also passively transported, was similarly affected. It appears that hyperpolarization and depolarization must be accompanied by approximately proportional increases and decreases in channel resistance since Na/sup +/ influx is not affected by polarization. 10 references, 3 figures, 4 tables.
- Research Organization:
- Illinois Univ., Urbana (USA). Dept. of Plant Biology
- DOE Contract Number:
- AC02-76EV00790
- OSTI ID:
- 6223401
- Report Number(s):
- DOE/EV/00790-1; ON: DE85001809
- Resource Relation:
- Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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CALCIUM
MEMBRANE TRANSPORT
ATP-ASE
CATIONS
CELL MEMBRANES
INDOLES
MAIZE
PLANT CELLS
POTASSIUM
ROOTS
ACID ANHYDRASES
ALKALI METALS
ALKALINE EARTH METALS
AROMATICS
AZAARENES
AZOLES
CELL CONSTITUENTS
CEREALS
CHARGED PARTICLES
ELEMENTS
ENZYMES
GRASS
HETEROCYCLIC COMPOUNDS
HYDROLASES
IONS
MEMBRANES
METALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHOHYDROLASES
PLANTS
PYRROLES
550300* - Cytology