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.

Evaluation of seed morphology characteristics of Alnus taxa in Iran

“…According to seed morphological UPGMA tree, three subspecies of A. glutinosa were close together. Similar results were reported by Shayanmehr et al (2014) and Gholamiterojeni et al (2019). They investigated morphological features and phylogenetic relationship using molecular ITS markers of some Alnus taxa and reported that these sub-species had very similar features.…”

“…The results of investigation revealed the suitability of ultrastructure characteristics such as a micro-morphological structure for solving the taxonomical ambiguities in this genus. In more recent morphological characteristics, both varieties of A. subcordata placed far from each other in different groups (Gholamiterojeni et al, 2019). Quantitative seed morphological characteristics varied among the taxa and could be used as the diagnostic features in taxa identification, as shown by PCA bi-plot.…”

“…For example, Shayanmehr et al (2014) evaluated morphological characteristics of different Alnus taxa in Iran. The molecular phylogeny of the genus according to two DNA barcode markers was not congruent with the last morphological classifications (Hosseinzadeh-Colagar et al, 2016), and Gholamiterojeni et al (2019) performed a revision of this genus in the country using molecular ITS markers and morphological characters and recognized some new taxa. But we could not find any study related to seed micromorphology of Alnus in Iran.…”

“…In this regard, Alnus phylogenetic analyses revealed that this genus is a monophyletic group (Murai, 1964;Navarro et al, 2003;Gholamiterojeni et al, 2019). Chen and Li (2004) applied sequences of nuclear ribosomal DNA (ITS region) to detect phylogenetic relationships of the genus and recognized three major clades including subgenera Alnus, Alnobetula (Ehrhart.)…”