LAUSR

The healthy properties of the Mediterranean diet are mainly attributed to the consumption of Extra Virgin Olive Oil (EVOO). Tunisia as an important producer of olive oil is characterized by a diverse varietal heritage. The aim of this work was to identify the chemical and molecular specificities of nineteen Tunisian olive cultivars cultivated under arid conditions. The study of the genetic variability of nineteen accessions of olive cultivars was based on two different molecular markers; Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) using 5 and 9 primers respectively. The accessions have been fingerprinted and all primers produced 179 PCR bands. 36 RAPD and 94 ISSR polymorphic bands were identified. The chemical characterization of EVOOs from the nineteen studied varieties was based on their fatty acids and phenolic profiles. Principal component analysis was accomplished according to the phenolic contents. It allowed distinguishing four groups of cultivars. Total phenols of Dhokar Nafti and Fougi Gtar cultivars reached 1010 mg per kg. For the fatty acid compositions, thirteen compounds were identified and oleic acid was the most abundant one with 80.66 g per 100 g and 79.19 g per 100 g of the total fatty acid composition for the varieties Rakhmi and Boudaoud respectively. Based on stepwise multiple regression analysis (MRA), 57 RAPD and ISSR markers were found associated with different biochemical traits. ISSR marker UBC807 1000bp was significantly associated with five traits including oleic acid, linoleic acid, linolenic acid, hydroxytyrosol and tyrosol compounds. It can be used as potential marker in marker-assisted selection for improvement of olive oil quality with high phenolic and fatty acid contents.