-tocopherol methyltransferase gene sequencing and SNP discovery associated with olive oil quality

The olive tree and olive oil are among the first things that come to mind throughout history when the M-diterranean geography is mentioned. Thus the fruit of the olive is very important in the agriculture of the Mediterranean region as a source of olive oil; it is one of the basic components of Mediterranean cuisine. gamma-tocopherol methyltransferase (GTMT), a key enzyme in the tocopherols biosynthesis pathway, is involved in the conversion of delta-and gamma-tocopherol to beta-and alpha-tocopherol, respectively. In fact, it plays an important role in the alpha-tocopherol composition and the quality of olive oil. A total of 14 olive cultivars (Olea europaea L.) were used in the present work. The materials were collected from diverse areas of Tunisia and to make a comparison four cultivars originating from Greece, Algeria, Morocco, and Spain were included. Young leaves of cultivars used for DNA extractions. PCR amplified the Vte4 gene from 14 olive cultivars and verified by electrophoresis on a 2% agarose gel for each variety. DNA sequencing of the olive cultivars revealed several single-nucleotide polymorphisms (SNPs). Statistical and bioinformatics analysis draw attention to some associations between some of the single nucleotide polymorphisms (SNPs), tocopherols contents and oleic acid content. In fact, two significant associations are obtained between SUBS24 and both total-tocopherols and beta-tocopherol. Moreover, dendrograms showed a correlation between genetic diversity and chemical characteristics which makes the Vte4 more in terms of levels.