Abstract
Nitrocellulose tissue prints immunoblotted with 9.5 cellulase antibody were used to demonstrate areas of cellulase localization within Phaseolus vulgaris explants on exposure to ethylene. The 9.5 cellulase was induced in the distal and proximal abscission zone and in the stem. In both abscission zones, the 9.5 cellulase was found in the cortical cells of the separation layer, which develops as a narrow band of cells at the place where fracture occurs. The enzyme was also found associated with the vascular traces of the tissues adjacent to the separation layer extending through the first few millimeters at each side of the separation layer. The two abscission zones differed in the way that cellulase distributed through the separation layer as abscission proceeded. In the distal zone, cellulase appeared first in the cells of the separation layer adjacent to vascular traces and extended toward the periphery. In the proximal zone, 9.5 cellulase accumulated first in the cortical cells that lie in the adaxial side and then extended to the abaxial side. In response to ethylene, 9.5 cellulase was also induced in the vascular traces of the stem and the pulvinus without developing a separation layer. The role of 9.5 cellulase in the vascular traces is unknown. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblotting with 9.5 cellulase antibody identified the same 51-kilodalton protein in both abscising and nonabscising tissues. Therefore, the determinant characteristic of the abscission process is the induction of 9.5 cellulase by cortical cells in the separation layer, and this implies that these cells have a unique mechanism for initiating 9.5 cellulase synthesis.
Full Text
The Full Text of this article is available as a PDF (3.2 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Del Campillo E., Durbin M., Lewis L. N. Changes in Two Forms of Membrane-Associated Cellulase during Ethylene-Induced Abscission. Plant Physiol. 1988 Nov;88(3):904–909. doi: 10.1104/pp.88.3.904. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mauch F., Staehelin L. A. Functional Implications of the Subcellular Localization of Ethylene-Induced Chitinase and [beta]-1,3-Glucanase in Bean Leaves. Plant Cell. 1989 Apr;1(4):447–457. doi: 10.1105/tpc.1.4.447. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morre D. J. Cell wall dissolution and enzyme secretion during leaf abscission. Plant Physiol. 1968 Sep;43(9 Pt B):1545–1559. [PMC free article] [PubMed] [Google Scholar]
- Reid P. D., Strong H. G. Cellulase and Abscission in the Red Kidney Bean (Phaseolus vulgaris). Plant Physiol. 1974 May;53(5):732–737. doi: 10.1104/pp.53.5.732. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tucker M. L., Sexton R., Del Campillo E., Lewis L. N. Bean abscission cellulase : characterization of a cDNA clone and regulation of gene expression by ethylene and auxin. Plant Physiol. 1988 Dec;88(4):1257–1262. doi: 10.1104/pp.88.4.1257. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Varner J. E., Taylor R. New ways to look at the architecture of plant cell walls : localization of polygalacturonate blocks in plant tissues. Plant Physiol. 1989 Sep;91(1):31–33. doi: 10.1104/pp.91.1.31. [DOI] [PMC free article] [PubMed] [Google Scholar]