Molecular Characterization of Solanum tuberosum's ADG2 Fragment Associated with Ryadg

Potato virus YNTN (PVYNTN) causes loss of potato yield and quality in Egypt and worldwide. This study aims to compare nucleotide sequence of ADG2 gene fragment in a wild potato line resistant to PVYNTN-carrying Ryadg, Solanum tuberosum L. subsp. andigena clone 17609 (R+adg), and line susceptible to PVYNTN non-carrying Ryadg (S-adg). We amplified ADG2 fragments from six potato lines with different genetic backgrounds by PCR and results showed one amplicon of 355 bp in all the examined potato lines. Two fragments from each resistant line (R+adg), and susceptible line (S-adg) were sequenced after purification using the ABI PRISM sequencer model 310. BLAST analysis of Ryadg from the resistance line and the susceptible line matched 98.41 and 96.02% with the ADG2 gene in S. tuberosum recorded in GenBank, respectively. The sequence comparison of the ADG2 fragments revealed ten and three differences at nucleotide and amino acid sequence levels respectively, between the resistance line having Ryadg and those lacking this gene. In addition, the 3D models of ADG2 proteins of R+adg and S-adg lines were evaluated by Ramachandran plot, which demonstrated that the homology modelling process was trusted. Therefore, the comparison of nucleotide sequences between the resistant line and the susceptible ones will lead to the identification of molecular markers, which will be used in potato breeding programs as marker-assisted selection to discriminate potato lines carrying Ryadg from those lacking this gene.