Abstract
Plants form and emit a bouquet of volatile compounds upon pathogen or herbivore attack. These volatiles are involved in indirect defense to recruit an organism to eliminate them as well as in direct defense to repel them. Furthermore, plants can perceive the volatiles and prime themselves against a prospective attack. Carbon six aldehydes are the first-formed volatile compounds upon pathogen or herbivore attack. Thus, it is assumed that C6-aldehydes might be involved in plant-plant communication.
When Arabidopsis was exposed to (E)-2-hexenal vapor, upregulation of some defense genes, lignification of cell walls, accumulation of antifungal compounds, and enhanced resistance to gray mold disease could be observed. Jasmonate- and ethylene-dependent signalings were involved in the response, but salicylate-dependent signalings are not. Interestingly, a mutant deficient in glutathione synthesis failed in the response. Based on the results, I would like to propose the volatile aldehyde-perception mechanism and its ecological significance.
