Publications

• Activation of glucosidase via stress-induced polymerization rapidly increases active pools of abscisic acid.

  Lee K.H., Piao H.L., Kim H.-Y., Choi S.M., Jiang F., Hartung W., Hwang I., Kwak J.M., Lee I.-J., Hwang I.

  Abscisic acid (ABA) is a phytohormone critical for plant growth, development, and adaptation to various stress conditions. Plants have to adjust ABA levels constantly to respond to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning ABA levels remain elusiv ... >> More

  Abscisic acid (ABA) is a phytohormone critical for plant growth, development, and adaptation to various stress conditions. Plants have to adjust ABA levels constantly to respond to changing physiological and environmental conditions. To date, the mechanisms for fine-tuning ABA levels remain elusive. Here we report that AtBG1, a beta-glucosidase, hydrolyzes glucose-conjugated, biologically inactive ABA to produce active ABA. Loss of AtBG1 causes defective stomatal movement, early germination, abiotic stress-sensitive phenotypes, and lower ABA levels, whereas plants with ectopic AtBG1 accumulate higher ABA levels and display enhanced tolerance to abiotic stress. Dehydration rapidly induces polymerization of AtBG1, resulting in a 4-fold increase in enzymatic activity. Furthermore, diurnal increases in ABA levels are attributable to polymerization-mediated AtBG1 activation. We propose that the activation of inactive ABA pools by polymerized AtBG1 is a mechanism by which plants rapidly adjust ABA levels and respond to changing environmental cues. << Less

  Cell 126:1109-1120(2006) [PubMed] [EuropePMC]

• Effect of ABA-beta-D-glucopyranosyl ester and activity of ABA-beta-D-glucosidase in Arabidopsis thaliana.

  Kato-Noguchi H., Tanaka Y.

  Exogenously applied ABA-beta-D-glucopyranosyl ester (ABA-GE) inhibited hypocotyl growth of Arabidopsis seedlings at concentrations greater than 0.3 micromol/L, and the concentration for 50% inhibition of hypocotyl growth was 1.8 micromol/L. ABA-beta-D-glucosidase activity in Arabidopsis seedlings ... >> More

  Exogenously applied ABA-beta-D-glucopyranosyl ester (ABA-GE) inhibited hypocotyl growth of Arabidopsis seedlings at concentrations greater than 0.3 micromol/L, and the concentration for 50% inhibition of hypocotyl growth was 1.8 micromol/L. ABA-beta-D-glucosidase activity in Arabidopsis seedlings was 17 nmol/mg protein/mim and increased by exogenously applied ABA-GE. The pH optimum of this enzyme in crude extract of Arabidopsis seedlings was 6.0 for the assay in the ABA-GE to ABA direction and its K(m) value for ABA-GE (pH 6.0) was 0.41 mmol/L. These results suggests that exogenously applied ABA-GE may be absorbed by roots and hydrolyzed by ABA-beta-D-glucosidase and librated free ABA may induce growth inhibition in Arabidopsis hypocotyls. << Less

  J. Plant Physiol. 165:788-790(2008) [PubMed] [EuropePMC]