Transcript Levels of CHL P Gene, Antioxidants and Chlorophylls Contents in Olive (Olea europaea L.) Pericarps: A Comparative Study on Eleven Olive Cultivars Harvested in Two Ripening Stages

The effects of ripening stage on the antioxidant content in olive pericarps were evaluated in eleven olive genotypes grown in the same bioagronomic conditions in Southern Italy. We examined the transcript levels of geranylgeranyl reductase (CHL P) gene and the content of tocopherols, phenolic compounds and chlorophylls in the pericarps. The examined genotypes showed an increase of CHL P transcripts during pericarps ripening. Significant differences were reported in the antioxidant proportions in the same cultivars at different pericarp ripening stage. We show an inverse correlation between phenols and tocopherols content. In particular, during the ripening phase, tocopherols increased rapidly in olive pericarps while phenolic compounds and chlorophyll levels declined significantly. The significant amounts of these antioxidants confirm the nutritional and medicinal value of olive drupes and its products (table olives and olive oil). We suggest, for the first time, a link between CHL P transcript levels and tocopherols content during the ripening of olive pericarps. Besides, we revealed that this trend of CHL P transcript levels during pericarps ripening is independent from the olive genotypes.