"Aging" of excised cotyledons plus the top part of the hypocotyl of Amaranthus tricolor seedlings was carried out by washing in distilled H(2)O for varying periods. This led to increased betacyanin accumulation during the subsequent 24-hour induction period in the presence of tyrosine and Na(+) + K(+) phosphate. Endogenous accumulation as well as that dependent on added benzyladenine and on add...

THE SENESCENCE (PROTEOLYSIS AND LOSS OF CHLOROPHYLL) OF ISOLATED LEAVES OF OAT SEEDLINGS IN THE DARK IS INHIBITED OR DELAYED BY COMPOUNDS OF SIX DIFFERENT TYPES: phenazine methosulfate, fusicoccin, alpha,alpha'-dipyridyl, cycloheximide, spermidine, and two cytokinins. In every case but the last, these compounds in optimum concentration caused the stomata to open and remain partly or completely ...

Guard cells are able to sense a multitude of environmental signals and appropriately adjust the stomatal pore to regulate gas exchange in and out of the leaf. The role of the microtubule cytoskeleton during these stomatal movements has been debated. To help resolve this debate, in vivo stomatal aperture assays with different microtubule inhibitors were performed. We observed that guard cells ex...

The leaf vascular bundle sheath cells (BSCs) that tightly envelop the veins, are a selective and dynamic barrier to xylem sap water solutes radially entering mesophyll cells. Under normal conditions, pH below 6 is presumably important for driving regulating transmembranal solute transport. Having discovered recently differentially high expression of BSC proton pump, AHA2, we now test hypothesis...