Effect of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle (Myrtus communis L.) in Morocco

Abstract

Myrtus communis L. is widely used as an aromatic and medicinal plant. In this work, we investigate the influence of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle. Samples of myrtle from different geographically distinct areas were measured and analysed for polyphenols, flavonoids, condensed tannins, and antioxidant activity using the DPPH test. The analysis of result reveals the significant variance among populations in terms of morphological traits and levels of secondary compounds, particularly in terms of polyphenols, flavonoids, condensed tannins, and reducing power. Correlations between certain studied traits and environmental conditions were recorded. Leaf size and methanolic leaf extract yields from Moroccan myrtle showed as good criteria for natural population selection. Precipitation, temperature, and altitude were determinants of variation in leaf morphological traits, extract yield, and their polyphenolic, tannin, and flavonoid compounds. Based on the studied traits, three major groups were identified with few clear geographical affiliations. The IZA population from the Western Rif and GHA from the Pre-Rif formed a separate group from the other populations, characterized by the highest extract yields. The BRA population from the central plateau formed a distinct isolated group from the others. This population, collected from a location with low annual rainfall values was the richest in tannins with relatively high levels of polyphenols and flavonoids compared to other populations. This means that drought affects the amount of polyphenols and flavonoids. The geographical structure of the third group is mixed, including the IKA and AGH (Pre-Rif) populations, BS and RAB from the Central Plateau, and BT from the Western Rif.