Calcium transport in protoplasts isolated from ml-o barley isolines resistant and susceptible to powdery mildew. [Hordeum vulgare L]

Journal Article · Thu Dec 01 00:00:00 EST 1988 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.88.4.1157· OSTI ID:6957856

Wrona, A F; Spanswick, R M; Aist, J R ^[1]

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1. Cornell Univ., Ithaca, NY (USA)

Free cytoplasmic calcium has been postulated to play a role in preventing powdery mildew in a series of homozygous ml-o mutants of barley, Hordeum vulgare L. Protoplasts isolated from 7-day-old plants of the ml-o resistant-susceptible (R-S) barley isolines, Riso 5678/3* {times} Carlsberg II R and S, were used to test for differences in fluxes of Ca{sup 2+} across the plasmalemma. Greater influx or lesser efflux might account for a higher free cytosolic Ca{sup 2+} postulated to exist in ml-o R mutants. Uniform patterns of uptake were maintained for 3 hours from solutions of 0.2 and 2 millimolar Ca{sup 2+}. Washout curves of {sup 45}Ca{sup 2+} from R and S protoplasts revealed three compartments - presumed to represent release from the vacuole, organelles, and the cytoplasm (which included bound as well as free Ca{sup 2+}). Uptake and washout did not differ between isolines. On the basis of recent determinations of submicromolar levels of free cytoplasmic Ca{sup 2+} and their initial rates of {sup 45}ca-labeled Ca{sup 2+} uptake, they show that measurement of the unidirectional influx of Ca{sup 2+} across the plasmalemma is not feasible because the specific activity of the pool of free cytoplasmic calcium increases almost instantaneously to a level that would result in a significant, but unknown, efflux of label. Similarly, measurement of the efflux of Ca{sup 2+} across the plasmalemma is not possible since the activity of the pool of free cytoplasmic calcium is a factor of 350 smaller than the most rapid component of the washout experiment. This pool of cytoplasmic free Ca{sup 2+} will wash out too rapidly and be too small to detect under the conditions of these experiments.

• OSTI ID: 6957856
• Journal Information: Plant Physiology; (USA), Vol. 88:4; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BARLEY
SENSITIVITY
CALCIUM COMPOUNDS
BIOCHEMICAL REACTION KINETICS
MILDEW
BIOLOGICAL EFFECTS
CALCIUM 45
MEMBRANE TRANSPORT
PLANT CELLS
TRACER TECHNIQUES
UPTAKE
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CEREALS
DAYS LIVING RADIOISOTOPES
EUMYCOTA
EVEN-ODD NUCLEI
FUNGI
GRASS
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LILIOPSIDA
MAGNOLIOPHYTA
NUCLEI
PARASITES
PLANTS
RADIOISOTOPES
REACTION KINETICS
550201* - Biochemistry- Tracer Techniques