Author
|
Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 2/19/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Although lipoxygenase was discovered in soybeans in 1932, many decades passed before it was acknowledged that the enzyme had a role in lipid-mediated signalling. Lipoxygenase is a component of a wound cascade resulting in plant defense from predator attack, as well as other functions. The best known part of a branching cascade is the biosynthesis of the jasmonate family of phytohormones. The jasmonates are known to regulate a number of defensive proteins, as well as storage and other proteins/enzymes. Additional branches of the pathway have been characterized, but are less studied for potential physiological significance. Our main subjects of study, maize and soybean, give contrasting views of how the cascade functions with potential implications regarding fungal parasitism. The main pathways in soybean seed are aldehyde and epoxide formation via lipoxygenases that oxidize pufa at both the 9- and 13-carbons. Among these pathways, a novel route was found leading to the cytotoxic and genotoxic 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal. The aldehydes, especially the latter two, are effective inhibitors of fungal growth; other potential functions are not yet known. In maize seed, the cascade is comprised mainly of a 9-carbon oxidizing lipoxygenase and allene oxide synthase, a jasmonate pathway enzyme. How these pathways may relate to an apparent lack of fungal resistance in maize is being studied. |
