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UMR DAP Equipe AFEF; International audience; Phenolic compounds are associated with the olive tree resistance to the leaf-spot disease caused by Spilocaea oleaginea were studied in different resistant, susceptible and intermediate cultivars. The HPLC analysis highlights 33 phenolic compounds distinguished according to their chromatographic and spectral characteristics into five phenolic families (hydroxycinnamic derivatives, flavonoids, verbascoside derivatives, tyrosol derivatives, oleuropein derivatives). The phenolic extract of the olive-tree is dominated by ten major compounds identified as rutin, luteolin-7-glucoside, oleuropein, versbacoside, tyrosol, apigenin and four other phenolic compounds not completely identified (oleuropein derivative, hydroxycinnamic derivative and two flavonol monoglucosides). No qualitative difference was observed between cultivars. However, the principal components analysis highlights two multifactorial components distinguishing the various cultivars according to their behaviour to the disease. The first component, identified as oleuropein aglycone, a hydroxycinnamic derivative and a flavonol monoglucoside contents, clearly distinguished the resistant cultivars from the susceptible and intermediately resistant cultivars. The resistant cultivars contain higher contents. The second component, identified as tyrosol derivative and an oleuropein derivative contents, distinguished the susceptible cultivars from the intermediately resistant cultivar which presents the highest contents. The role of these phenolic compounds in the defense and their use as biochemical markers in olive-tree resistance to S. oleaginea is discussed

E-mail Addresses: elmodafar@fstg-marrakech.ac.ma Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; To understand the resistance of the olive tree to the leaf-spot disease caused by Spilocaea oleagina, the constitutive and postinfectional synthesis phenolic compounds of the leaves were analyzed by HPLC in 110 genotypes F1 (susceptible cultivar “Picholine marocaine” x resistant cultivar “Picholine du Languedoc”) presenting of the differential behaviours to this disease (highly resistant, resistant, intermediate, susceptible & highly susceptible genotypes). The HPLC analysis distinguished 15 majors phenolic compounds according to their chromatographic and spectral characteristics into five phenolic families (hydroxycinnamic derivatives, flavonoids, verbascoside derivatives, tyrosol derivatives, oleuropein derivatives). No qualitative difference was observed between cultivars. Principal components analysis (PCA) highlighted three multifactorial components distinguishing the various genotypes according to their behaviour to the disease. These components were determined by the postinfectional contents of oleuropein and rutin and by the constitutive contents of tyrosol and its derivatives. The tyrosol and its derivatives were associated with constitutive resistance, whereas the oleuropein and rutin were associated with induced resistance. These results suggest that the activity ratio of the enzymes implied in various biosynthesis ways of these phenolic compounds and/or the expression rate of the corresponding genes would be at the origin of the resistance degree of olive tree to S. oleagina.