The role of ethylene in regulation of pectin-modifying enzymes and in pectin remodeling in pistils of Petunia axillaris.
Research Mentor(s)
Prody, Gerry; Singh-Cundy, Anu
Description
Pectins are extracellular polysaccharides containing 1,4-polygalacturonans, and are a major component of the cell walls of the pistil, the female reproductive structure in flowering plants. The arrival of pollen (which carry sperm cells) triggers production of the gaseous plant hormone, ethylene. Previous work in the Prody lab has shown that treatment of pistils with ethylene leads to reduction in the molecular mass of pectin fractions extracted from pistils, with a commensurate release of oligosaccharides fragments. We hypothesize that pectin-modifying enzymes, such as pectin esterases (PE), are likely leading to this reduction. Gel diffusion assays measuring esterase activity revealed constitutive presence of pectin esterase. Results suggest esterase activity is suppressed by a pectin esterase inhibitor (PEI) that forms a complex with the esterases, and this inhibitory complex can be dissociated with an increase in NaCl (300 mM). In our working model, ethylene triggers dissociation of the PE-PEI complex, rendering the pectins susceptible to partial depolymerization. The consequent changes in the physicochemical properties of the extracellular matrix soften the extracellular matrix, facilitating pollen tube growth and fertilization.
Document Type
Event
Start Date
14-5-2015 10:00 AM
End Date
14-5-2015 2:00 PM
Department
Chemistry
Genre/Form
student projects; posters
Subjects – Topical (LCSH)
Petunias; Petunias--Pollen management; Pollination
Type
Image
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this documentation for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Language
English
Format
application/pdf
The role of ethylene in regulation of pectin-modifying enzymes and in pectin remodeling in pistils of Petunia axillaris.
Pectins are extracellular polysaccharides containing 1,4-polygalacturonans, and are a major component of the cell walls of the pistil, the female reproductive structure in flowering plants. The arrival of pollen (which carry sperm cells) triggers production of the gaseous plant hormone, ethylene. Previous work in the Prody lab has shown that treatment of pistils with ethylene leads to reduction in the molecular mass of pectin fractions extracted from pistils, with a commensurate release of oligosaccharides fragments. We hypothesize that pectin-modifying enzymes, such as pectin esterases (PE), are likely leading to this reduction. Gel diffusion assays measuring esterase activity revealed constitutive presence of pectin esterase. Results suggest esterase activity is suppressed by a pectin esterase inhibitor (PEI) that forms a complex with the esterases, and this inhibitory complex can be dissociated with an increase in NaCl (300 mM). In our working model, ethylene triggers dissociation of the PE-PEI complex, rendering the pectins susceptible to partial depolymerization. The consequent changes in the physicochemical properties of the extracellular matrix soften the extracellular matrix, facilitating pollen tube growth and fertilization.