Contribution to the molecular taxonomy of mastic tree morphotypes on Chios Island

Abstract

Background: The mastic tree (formal name: Pistacia lentiscus var. Chia) is extensively cultivated on the southern part of the Greek island of Chios. Its extensive cultivation is due to the production of a special resin, known as mastic gum, or mastiha, which is widely used in several dietary, pharmaceutical and other products since ancient times. Mastic tree is an evergreen, dioecious (consisting of male and female individuals), woody plant. Furthermore, a number of morphological characteristics suggest the existence of several different plant groups, called here “morpho-varieties”, but it is probable that there exist an unknown number of different, deviating genotypes on the island. Nevertheless, five major morphologically determined morpho-varieties of mastic tree are mainly cultivated, namely “Votomos”, “Maroulitis”, “Mavroschinos”, “Stenophyllos” and “Fardyphyllos”. The morpho-varieties exhibit mostly, but not always, distinct morphology, on which their taxonomy was initially based. Since it is observed that different plant populations differ in the quantity and quality of the produced resin, it is important to explore whether these differences have a genetic basis, or are due to other factors, such as agricultural practices, or soil composition. To this end, the genetic diversity among these five morpho-varieties and within each one of them was investigated in the present study, using in a first approximation their Random Amplified Polymorphic DNA profiles and subsequently the sequence divergence of their Internal Transcribed Spacer regions 1 and 2. Results: The results confirm the existence of a considerable genotypic diversity among the five morpho-varieties studied and, furthermore, reveal the existence of genotypic diversity within each one of them, as well as the existence of a number of further deviating genotypes. The possibility, this diversity to be partly a result of reticulate evolution events is also discussed. Conclusions: This study provides evidence that the population of cultivated mastic trees on the island of Chios consists mainly of two species, i.e. Pistacia lentiscus and Pistacia x saportae, although it is clear that there also exist genetically deviating mastic trees, as well as individual plants, probably produced through hybridization between the two afore mentioned species.

Keywords

• anacardiaceae, genetic diversity, internal transcribed spacers, random amplified polymorphic dna, reticulate evolution, pistacia lentiscus, pistacia x saportae