First clues on a jasmonic acid role in grapevine resistance against the biotrophic fungus Plasmopara viticola

Plants are sessile organisms being constantly under a wide array of environmental pressures. Their resistance against biotic stress is regulated by phytohormones, of which jasmonic acid (JA) plays an important role against necrotrophic pathogens and herbivorous insects whereas salicylic acid (SA) plays a crucial role in plant defence against biotrophic and hemi-biotrophic pathogens, as well as in the establishment of systemic acquired resistance. Plasmopara viticola is a biotrophic oomycete responsible for one of the most important diseases in viticulture. Recent studies have shown that JA-signalling may be playing an important role on grapevine resistance against this biotrophic pathogen. Expression of enzymes associated to JA biosynthesis (LOX2, AOS, AOC, OPR3), activation (JAR1) and signalling (COI1) was analysed in two Vitis vinifera genotypes with different degrees of resistance towards P. viticola. Our results provide the first clues for a JA-signalling role in grapevine defence against this fungal biotroph.