Cytochrome Oxidase and Mitochondrial Protein in Extracts of Leaves of Nicotiana glutinosa L. Infected with Tobacco Mosaic Virus

Leaves of N. glutinosa were inoculated with tobacco mosaic virus,and infection allowed to develop in situ or in discs cut fromthe leaves and floated on water or culture solution. Extracts,made from the leaves and discs when their respiration was greaterthan that of comparable uninfected tissue, contained amountsof protein N, chlorophyll, glycollic oxidase, and mitochondrialprotein N, similar to those in extracts from uninfected tissue,but slightly less cytochrome oxidase and considerably more polyphenoloxidase.No evidence was obtained for the view that the virus-inducedrespiration reflects an increase in the amount of mitochondrialmaterial.     

Can aspirin help identify leaf proteins active in defence responses?

The oxidation of arachidonic acid in vertebrate tissues is briefly compared to the oxidation of linolenic acid in plants. Both give rise to bio‐active molecules containing cyclopentane rings, the prostaglandins and jasmonic acid respectively. Both oxidations are inhibited by salicylic acid, aspirin and other non‐steroidal, anti‐inflammatory drugs. Aspirin is known to inhibit the cyclising enzyme, cyclo‐oxygenase in animal tissues. By contrast it is thought to inhibit allene oxide synthase (AOS) rather than the analogous cyclising enzyme in plants. This conclusion is based on studies of an unusual isoform of AOS, and it is suggested that a search should be made for aspirin‐acetylatable proteins in extracts of the leaves of temperate crop plants. The possible reaction of aspirin with the unusual AOS produced by sea corals is briefly considered.