Abstract

Fusarium oxysporum f.sp. elaeidis (Foe) is a fungus that attacks oil palm and affects its production. This study aimed at characterizing phenolic compounds and evaluating their spatiotemporal evolution in two cultivars (sensitive and tolerant to fusariosis). For this, total phenols were quantified during the latency period [0 to 28 Days After Inoculation (DAI)] of Foe. Thereafter, phenolic extracts from plant organs (roots and pseudobulbs) were used for in vitro inhibition tests of Foe spore germination. Lastly, Gas Chromatography coupled to Mass Spectrophotometry (GC-MS) was used to detect polyphenols. These results revealed that phenolic reaction in roots was earlier (1st DAI or T0) in the tolerant cultivar than in the sensitive (8th DAI). However, it occurred simultaneously in the pseudobulbs (3rd DAI) in both cultivars. Spore Germination Inhibition Rate (SGIR) of Foe reached 100% in the tolerant cultivarb against the sensitive cultivar in which a maximum rate of 49, 64% was recorded. GC-MS revealed that in roots, para-hydroxybenzoic acid is a phytoanticipin while meta-hydroxybenzoic acid is a phytoalexin. However, in pseudobulbs, these two polyphenols are phytoalexins. These results will allow exploring the biosynthetic pathway of phenolic acids in order to improve the phenolic response of disease-sensitive but productive hybrids.

Key words: Fusarium oxysporum f.sp. elaeidis, inhibition, polyphenols, GC-MS, meta-hydroxybenzoic acid, para-hydroxybenzoic acid.