Phylogenetic Analysis of Four Selected Asteraceae Species Using ITS Molecular Markers

• Zahraa earif yahyaa*1, Ashwaq T. Hameed2 and Rasha Abd Al Hadi Al Tarawneh3

  Author

    The Asteraceae family is one of the largest and most diverse families of flowering plants worldwide, comprising over 23,000 species distributed across a wide range of geographic environments. Molecular markers have become essential tools in taxonomic and evolutionary studies of plants, particularly in groups where species are difficult to distinguish based solely on morphological characteristics. The Internal Transcribed Spacer (ITS) region is one of the most widely used molecular markers in plant systematics and phylogenetic studies due to its high evolutionary rate and strong discriminatory power among closely related species. This study aimed to assess genetic diversity and infer phylogenetic relationships among four plant species belonging to the Asteraceae family using ITS region sequencing (n = 4). Plant samples were collected from several areas in Anbar Governorate, Iraq. Total genomic DNA was extracted using the CTAB method, and the ITS region was amplified using polymerase chain reaction (PCR) with the primers ITS1F and ITS4R. The amplified products were confirmed on agarose gel, showing clear bands of approximately 600–700 bp, consistent with the expected size of the ITS region in angiosperms. The obtained sequences were compared with reference sequences in the GenBank using BLAST analysis, revealing high sequence similarity (97–100%), which confirmed accurate species identification. Phylogenetic analysis was performed using the Maximum Likelihood method with 1000 bootstrap replicates. The results showed that the studied species were divided into two main clades. The first clade included Centaurea caballeroi, Artemisia transiliensis, and Sonchus brachyotus, where the closest genetic relationship was observed between C. caballeroi and S. brachyotus, with genetic distance values ranging from 0.183 to 0.193, while A. transiliensis showed higher divergence (0.376). In contrast, Silybum marianum formed a distinct separate clade with the highest genetic distance, indicating clear genetic differentiation. Overall, the results demonstrate the effectiveness of ITS-based DNA barcoding in resolving phylogenetic relationships within the Asteraceae family and highlight its importance in plant molecular taxonomy and biodiversity studies.

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