Molecular identification of the genus Betula based on ITS sequence data and its secondary structure in Iran

Nucleotide sequences of internal transcribed spacer (ITS) of nuclear ribosomal DNA were used to infer the phylogeny and molecular taxonomy status of Betula species. Three remnant populations of Betula from Hyrcanian forests and one population from Zagros forest were selected. Leaf DNA were extracted and ITS regions were amplified on the selected samples. Entire lengths of the ITS1-5. 8S-ITS2 region were 610-611 bp for all of the studied Betula samples and 611 bp for Iranian samples. Maximum similarity in nucleotide composition and minimum genetic distance of Iranian Betula were observed with Betula pendula from subgenus of Betula. According to character based method، Iranian Betula was distinguished from other Betula species due to having unique nucleotide at position 209. Four secondary structure ITS2 type were recognized for all of the studied Betula species. Construction of the phylogenetic trees of ITS data supported monophyly of the genus Betula and divided into three major groups with more than 73% bootstrap support. The first Group comprises four minor groups by which Iranian Betual with B. pendula was located in Clade I.