الفهرس 
Introduction and Aims of the studyOnly 14 pages are availabe for public view
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Abstract
The study aims to identify different species of nettle at the molecular level in various regions of Egypt using DNA barcoding and the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) primer. All collected samples of nettle were sequenced; the sequences had been assigned to the National Center for Biotechnology
Information (NCBI), and accession numbers had been obtained. The nucleotide sequence of the ribulose-bisphosphate carboxylase (rbcL) gene from collected Urtica sp samples was also aligned with other published rbcL genes from the GenBank
database (http://www.ncbi.nlm.nih.gov) using BLAST (https://blast.ncbi.nlm.nih.gov/Blast.cgi?PROGRAM=blastn&PAGE_TYPE=BlastSea
rch&LINK_LOC=blasthome). The phylogenetic tree was performed for rbcL gene between the studied samples, which were collected from some regions in Egypt, and others that were found in GenBank using MEGA11 software program.
The second aim is to test the antimicrobial activity of ethanolic extracts of Urtica urens and Urtica pilulifera against some pathogenic bacteria. Seven different bacteria
strains were used to screen the possible antimicrobial activity of Urtica sp. using the disk diffusion method.
The following are the outcomes of this work:
1- DNA Barcoding:
- The PCR analysis using specific primers showed one band with a length of
approximately 500 to 700 base pairs (bp).
Sequence alignment and phylogenetic tree of ribulose-bisphosphate carboxylase gene The results showed that some of the rbcL gene’s nucleotide sequence aligned with others in GenBank and had 99% similarity to Urtica urens, similar to the morphological level. Other studied sequences aligned with others in GenBank had similarities with Urtica triangularis subsp. pinnatifida between 96% and 97% of the time, but at
the morphological level, it was similar to Urtica pilulifera.
The sequences of Urtica urens and Urtica pilulifera had been assigned to the National Center for Biotechnology Information (NCBI), and accession numbers had been obtained for both species. The accession numbers are OP781303 for Urtica urens and OP781302 for Urtica pilulifera.
2- Antimicrobial activity using Disk diffusion method:
The extracts of Urtica urens and Urtica pilulifera have the ability to inhibit all tested bacteria. The mean values of inhibition zones of ethanolic extracts of Urtica urens were significantly higher (P<0.05) than commercial antibiotic against Escherichia coli,
Bacillus thuringiensis, and Erwinia amylovora. While the mean values of inhibition zones of ethanolic extracts of Urtica pilulifera were significantly higher (P<0.05) than commercial antibiotic against Agrobacterium tumefaciens, Bacillus thuringiensis, and
Erwinia amylovora.