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Updated: May 18, 2026
10:26
The Infiltration-centrifugation Technique for Extraction of Apoplastic Fluid from Plant Leaves Using Phaseolus vulgaris as an Example
Published on: December 19, 2014
Endogenous ascorbate restrains apoplastic peroxidase activity during sunflower leaf development.
1Instituto de Investigaciones Biológicas-FCEyN, Universidad Nacional de Mar del Plata, CONICET, Mar del Plata, Argentina. mpinedo@mdp.edu.ar
Plant Biology (Stuttgart, Germany)
|October 10, 2012
Summary
Plant leaf growth is regulated by peroxidase enzymes and their inhibitors. Ascorbate in growing leaves restrains peroxidase activity, which is released upon growth cessation, allowing cell wall stiffening.
Area of Science:
- Plant Biology
- Biochemistry
- Cell Biology
Background:
- Apoplastic enzymes, such as peroxidases, play crucial roles in regulating plant cell elongation.
- Extracellular inhibitors are known to modulate the activity of these enzymes.
- Understanding enzyme-inhibitor interactions is key to deciphering mechanisms controlling leaf development.
Purpose of the Study:
- To investigate the role of enzyme-inhibitor interactions in controlling Helianthus annuus leaf development.
- To characterize the relationship between peroxidase activity and its inhibitors in the apoplast during leaf growth.
Main Methods:
- Isolation of intercellular washing fluids from Helianthus annuus leaves of varying ages via vacuum infiltration and centrifugation.
- Assay of peroxidase activity using tetramethylbenzidine as a substrate.
- Chemical characterization and quantification of extracellular inhibitors, identified as ascorbate.
Main Results:
- Peroxidase activity increased with leaf development, peaking post-expansion.
- Ascorbate was identified as an extracellular inhibitor co-localizing with peroxidase in the apoplast.
- A significant negative correlation was observed between peroxidase activity and ascorbate concentration.
Conclusions:
- Ascorbate concentration in growing leaves effectively inhibits peroxidase activity in planta.
- Cessation of leaf growth is associated with a decrease in extracellular ascorbate, relieving peroxidase inhibition.
- This regulation by ascorbate influences cell wall stiffening and growth termination.
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