Fuente: WIPO "tomato" Described are plant defense elicitors or plant elicitor compositions and their use in, for example, agricultural applications, more particularly, to protect plants against pests or pathogens. This includes the corresponding methods of and uses in the protection of plants and crops by application of these plant defense elicitors or plant elicitor compositions. The active ingredient(s) of the plant defense elicitor or plant elicitor comprise lignin-derived phenolic oligomers with a degree of polymerization (DP) of 2 to 8 (preferably 2-4) (such as lignin-derived dimeric (diphenolic), lignin-derived trimeric compounds (triphenolic) and lignin-derived tetrameric compounds) and the engineered or synthesized structurally similar compounds. More particularly, described is a plant defense elicitor wherein an active ingredient of the plant defense elicitor comprises depolymerized lignin containing as active ingredient lignin-derived phenolic oligomers (such as lignin-derived dimeric compounds (diphenolic), lignin-derived trimeric compounds (triphenolic), and lignin-derived tetrameric compounds) and engineered or synthesized structurally similar compounds.