Molecular Characterization of Potato Virus Y (PVY) Strains in Iraq and Evaluation of Induced Virus Resistance in Three Potato Cultivars Using Natural Biological Control Agents

Abstract

A field survey was conducted in major potato-growing regions in Iraq, including Baghdad, Al-Anbar, and Salah Al-Din provinces, to identify the prevalent Potato virus Y (PVY) strains. A field experiment was carried out in Al-Alam district, Salah Al-Din province during the 2025 autumn season. Three PVY strains (PVYᵒ, PVYᴺᵀᴺ, and PVY^C) were distinguished using RT-PCR with strain-specific primers, with amplified bands of 335 bp for PVYᵒ, 918 bp for PVYᴺᵀᴺ, and the expected fragment of PVY^C. Electrophoretic separation confirmed successful amplification of these strains in the samples tested. Chroococcus turgidus extract exhibited high antiviral activity by significantly reducing infection rate and severity, reaching 20.00% and 27.00%, respectively. Moreover, Ch. turgidus treatment produced the highest peroxidase activity in the cultivar ‘Topaze’ at 2.161 U/mg protein, followed by the Bion® treatment (1.956 U/mg protein), as compared with the infected control (1.003 U/mg protein). Both Ch. turgidus and Bion® treatments achieved the highest chlorophyll content values of 43.66 and 43.00 SPAD, respectively, in the potato cultivar ‘Topaze’, compared to the untreated infected control (35.00 SPAD). Additionally, tannin extract treatment resulted in the highest plant height of 78.00 cm. The Ch. turgidus treatment produced a significantly higher tuber yield than the other treatments that produced the highest tuber yield of 1,600 g per plant. These findings highlighted the promising potential of natural biological agents in suppressing PVY infection and enhancing the physiological performance and potato productivity under field conditions.

Keywords:

Potato virus Y, PVY strains, characterization, induced resistance, biological control.