2013/07/26 by Anna Nakashima, Stephan H. von Reuß, Hiroyuki Tasaka +8 · 1 citation
Biochemistry, Genetics and Molecular Biology · #Plant biochemistry and biosynthesis #Lipid metabolism and biosynthesis #Plant Gene Expression Analysis
paper · pdf · doi:10.1074/jbc.m113.487959
openalex publication_date 2013/07/26 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/29
Green leaf volatiles (GLVs) consisting of six-carbon aldehydes, alcohols, and their esters, are biosynthesized through the action of fatty acid hydroperoxide lyase (HPL), which uses fatty acid hydroperoxides as substrates. GLVs form immediately after disruption of plant leaf tissues by herbivore attacks and mechanical wounding and play a role in defense against attackers that attempt to invade through the wounds. The fates and the physiological significance of the counterparts of the HPL reaction, the 12/10-carbon oxoacids that are formed from 18/16-carbon fatty acid 13-/11-hydroperoxides, respectively, are largely unknown. In this study, we detected monogalactosyl diacylglycerols (MGDGs) containing the 12/10-carbon HPL products in disrupted leaf tissues of Arabidopsis , cabbage, tobacco, tomato, and common bean. They were identified as an MGDG containing 12-oxo-9-hydroxy-( E )-10-dodecenoic acid and 10-oxo-7-hydroxy-( E )-8-decenoic acid and an MGDG containing two 12-oxo-9-hydroxy-( E )-10-dodecenoic acids as their acyl groups. Analyses of Arabidopsis mutants lacking HPL indicated that these MGDGs were formed enzymatically through an active HPL reaction. Thus, our results suggested that in disrupted leaf tissues, MGDG-hydroperoxides were cleaved by HPL to form volatile six-carbon aldehydes and non-volatile 12/10-carbon aldehyde-containing galactolipids. Based on these results, we propose a novel oxylipin pathway that does not require the lipase reaction to form GLVs. Background: The pathway to form green leaf volatiles is important for plant defense against pathogens and herbivores. Results: Galactolipids with truncated oxoacids are formed as counterparts of green leaf volatiles. Conclusion: Galactolipid-hydroperoxides are substrates for hydroperoxide lyase. Significance: The biosynthetic pathway partly proceeds directly with galactolipids, without the involvement of lipases, to form free fatty acids.