Revision of Alnus (Betulaceae) in Iran using molecular ITS markers and morphological characteristics

Abstract

Alnus (Alder) is a genus of Betulaceae, which comprises more than 29 species in the world. According to different classifications of flora, eight taxa of the genus naturally grow in Iran and are distributed along the northern slope of Albourz Mountains in Iran (Hyrcanian forests). In the current research, we investigated morphological characteristics and phylogenetic relationships of 31 populations of the genus in Iran. Twenty-eight qualitative and quantitative traits were studied for morphological evaluation and ITS molecular marker was investigated for molecular study. We used MVSP, SPSS, MrBayes, RAXMLGUI, Mesquite 2.71, Modeltest 3.7 software packages for statistical analyses. Morphological features varied widely among the studied taxa and ANOVA test revealed significant difference for most of them. Moreover, the angle of leaf base, the leaf margin shape, the length and width of the leaf blade, fruits length, and the presence of hair on the petioles, young twigs, and buds were more variable morphological traits. The studied taxa were clustered separately in the UPGMA tree, PCA and PCO plots using morphological traits. In addition, CA-joined plot showed each taxon to have distinct morphological trait(s), which is useful in the identification of the taxa. Phylogeny analysis revealed that Alnus genus is a monophyletic group. Furthermore, the studied taxa were clustered separately in phylogenetic dendrogram. According to morphological and ITS data, we listed ten taxa of the genus in Iran and introduced A. hyrcana and A. longiflorescentia as two new species from Hyrcanian forests of Iran.