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A lipid-hydrolysing activity involved in hexenal formation
K Matsui1, S Kurishita, A Hisamitsu
1Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515, Japan. matsui@agr.yamaguchi-u.ac.jp
Biochemical Society Transactions
|February 15, 2001
Summary
Plant wounding releases short-chain aldehydes from lipids, crucial for defense. This study identifies a galactolipid-specific lipase as the key enzyme initiating this process in Arabidopsis.
Area of Science:
- Plant biochemistry
- Molecular biology
- Plant defense mechanisms
Background:
- Short-chain aldehydes like (3Z)-hexenal are plant defense compounds.
- Their formation involves lipid hydrolysis, lipoxygenase, and fatty acid hydroperoxide lyase activities.
- The enzyme responsible for the initial lipid-hydrolysing step remains largely unknown.
Purpose of the Study:
- To characterize the lipid-hydrolysing activity in short-chain aldehyde formation in Arabidopsis.
- To identify the specific lipids and enzymes involved in this pathway.
Main Methods:
- Homogenization of Arabidopsis leaves under aerobic and anaerobic conditions.
- Assay of short-chain aldehyde formation and fatty acid levels.
- Inhibition of hydrolysis using quinacrine, a lipase inhibitor.
- Analysis of lipid substrates, specifically monogalactosyldiacylglycerol.
Main Results:
- Rapid formation of (3Z)-hexenal upon homogenization, coinciding with decreased alpha-linolenic acid and C(16:3).
- Anaerobic conditions and lipase inhibitor quinacrine repressed aldehyde formation and hydrolysis.
- Trienoic acids within monogalactosyldiacylglycerol were the primary substrates hydrolyzed.
Conclusions:
- A lipolytic enzyme initiates short-chain aldehyde formation in Arabidopsis.
- This enzyme appears to be a galactolipid-specific lipase.
- Understanding this pathway enhances knowledge of plant defense responses.