Abstract
Calcium movement across primary roots of maize (Zea mays, L.) was determined by application of 45Ca2+ to one side of the root and collection of radioactivity in an agar receiver block on the opposite side. Ca movement across the root tip was found to be at least 20 times greater than movement across the elongation zone. The rapid movement of Ca across the tip was severely inhibited in roots from which the root cap had been removed. Ca movement across the tip was also strongly retarded in roots pretreated with 2,4-dinitrophenol or potassium cyanide. Orientation of roots horizontally had no effect on Ca movement across the elongation zone but caused a strong asymmetry in the pattern of Ca movement across the tip. In gravistimulated roots, the movement of Ca from top to bottom increased while movement from bottom to top decreased. The data indicate that gravistimulation induces polar movement of Ca toward the lower side of the root cap. An earlier report (Lee, Mulkey, Evans 1983 Science 220: 1375-1376) from this laboratory showed that artificial establishment of calcium gradients at the root tip can cause gravitropic-like curvature. Together, the two studies indicate that Ca plays a key role in linking gravistimulation to the gravitropic growth response in roots.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Chandra S., Chabot J. F., Morrison G. H., Leopold A. C. Localization of calcium in amyloplasts of root-cap cells using ion microscopy. Science. 1982 Jun 11;216(4551):1221–1223. doi: 10.1126/science.216.4551.1221. [DOI] [PubMed] [Google Scholar]
- Charbonneau H., Cormier M. J. Purification of plant calmodulin by fluphenazine-Sepharose affinity chromatography. Biochem Biophys Res Commun. 1979 Oct 12;90(3):1039–1047. doi: 10.1016/0006-291x(79)91931-4. [DOI] [PubMed] [Google Scholar]
- Cormier M. J., Charbonneau H., Jarrett H. W. Plant and fungal calmodulin: Ca2+-dependent regulation of plant NAD kinase. Cell Calcium. 1981 Aug;2(4):313–331. doi: 10.1016/0143-4160(81)90023-3. [DOI] [PubMed] [Google Scholar]
- Dela Fuente R. K., Leopold A. C. A role for calcium in auxin transport. Plant Physiol. 1973 May;51(5):845–847. doi: 10.1104/pp.51.5.845. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hale C. C., Roux S. J. Photoreversible calcium fluxes induced by phytochrome in oat coleoptile cells. Plant Physiol. 1980 Apr;65(4):658–662. doi: 10.1104/pp.65.4.658. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lee J. S., Mulkey T. J., Evans M. L. Reversible loss of gravitropic sensitivity in maize roots after tip application of calcium chelators. Science. 1983 Jun 24;220(4604):1375–1376. doi: 10.1126/science.220.4604.1375. [DOI] [PubMed] [Google Scholar]
- Lilley R. M. Isolation of Functionally Intact Rhodoplasts from Griffithsia monilis (Ceramiaceae, Rhodophyta). Plant Physiol. 1981 Jan;67(1):5–8. doi: 10.1104/pp.67.1.5. [DOI] [PMC free article] [PubMed] [Google Scholar]