Studies on the control of plant cell enlargement by cellular parameters
The overall goal of this grant was to conduct research that would illuminate the mechanisms by which the plant hormone auxin induces plant cells to enlarge. A large body of knowledge already existed concerning this process. To begin with, it had been demonstrated, primarily by this laboratory during previous grant periods, that the effect of auxin is to cause a loosening of the cell wall, which is followed by turgor-driven wall expansion and water uptake. The wall contains a series of load-bearing wall bonds which must be cleaved in order to loosen the wall. The identification of these load-bearing bonds is one goal of this research. We proposed that an initial action of auxin is to cause cells to excrete protons, and that the resulting acidification of the apoplast activated enzymes responsible for wall loosening. Evidence has been obtained that indicates that the proton excretion is due to an enhanced activity of the plasma membrane H{sup +} {minus}ATPase. A critical question is how auxin activates this enzyme. The third project concerned the role of wall calcium as part of load-bearing wall bonds. It has long been thought that apoplastic calcium crosslinks carboxyl groups in the wall pectic substances and stiffens the walls. We examined the role of calcium-bridges as load-bearing bonds in soybean hypocotyl cell walls in two ways. The first was to measure the viscoelastic extensibility of walls after addition of exogenous calcium or removal of endogenous calcium. The second approach was to determine if removal of wall calcium from walls while under tension resulted in wall extension, as predicted if the calcium-bridges were load-bearing bonds.
- Research Organization:
- Washington Univ., Seattle, WA (United States). Dept. of Botany
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG06-88ER13830
- OSTI ID:
- 5755024
- Report Number(s):
- DOE/ER/13830-2; ON: DE92004838
- Country of Publication:
- United States
- Language:
- English
Similar Records
Studies on the control of plant cell enlargement by cellular parameters: Progress report, July 1, 1987-June 30, 1988
Reevaluation of the effect of calcium ions on auxin-induced elongation
Related Subjects
CELL WALL
CHEMICAL BONDS
PLANT CELLS
ENZYME ACTIVITY
CALCIUM
ENZYMES
HORMONES
PROGRESS REPORT
SIZE
SOYBEANS
STIMULATION
ALKALINE EARTH METALS
CELL CONSTITUENTS
DOCUMENT TYPES
ELEMENTS
FOOD
METALS
ORGANIC COMPOUNDS
PLANTS
PROTEINS
VEGETABLES
550300* - Cytology
550200 - Biochemistry