Poster Title

The role of ethylene in regulation of pectin-modifying enzymes and in pectin remodeling in pistils of Petunia axillaris.

Research Mentor(s)

Gerry Prody, Anu Singh-Cundy

Affiliated Department

Chemistry

Sort Order

39

Start Date

14-5-2015 10:00 AM

End Date

14-5-2015 2:00 PM

Document Type

Event

Abstract

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.

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

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May 14th, 10:00 AM May 14th, 2:00 PM

The role of ethylene in regulation of pectin-modifying enzymes and in pectin remodeling in pistils of Petunia axillaris.

Chemistry

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.