Mycorrhizal infection, essential oil content and morpho-phenological characteristics variability in three mint species

This study investigated the natural variation of arbuscular mycorrhizal associations and variation in morpho-phenological characteristics and essential oil content of 40 accessions of Mentha species including Mentha spicata L., Mentha piperita L. and Mentha longifolia (L.) Hudson collected from 13 provinces of Iran. The colonization by Arbuscular Mycorrhizal Fungi (AMF) was naturally found in 38 accessions ranged from 1.4 to 71.8% of infection. There was a significant variation between and within species in terms of essential oil content differing from 0.30 to 3.33% beyond the previously reported range. Accessions collected from colder climate conditions exhibited significantly higher oil content than those from warmer conditions. M. longifolia had significantly higher oil content than the other two species. A high variation in fresh weight and leaf water content was also observed and higher mean values were obtained in accessions of M. piperita and M. longifolia, respectively. A dendrogram generated using the UPGMA algorithm classified the 40 accessions into four distinctive groups based on the species and discriminating characteristics. The high variability in naturally mycorrhizal infection, essential oil content and morpho-phenological characteristics suggests the possibility of improving mint accessions for horticultural and medicinal uses through selection in breeding programs.

► Mint has high capacity of forming symbiotic relationship with mycorrhizal species.
► Colder climate conditions may sustain mint variation with higher oil content.
► An accession with outstanding essential oil content (3.33%) was found in M. longifolia.