Identification and green synthesis of potato dry rot Fusarium falciforme silver nanoparticles, characterization and antibacterial activity.

Potato tubers collected from different areas showed the prevalence of dry rot with characteristic white mycelia like symptoms of Fusarium pathogen. Fusarium species from diseased tubers were isolated based on morphological features. 18 S-Internal Transcribed Spacer (ITS) and Translation Elongation factor 1-α (TEF1-α) based analysis followed by phylogenetic tree constructed using ITS, TEF1-α and RNA polymerase II subunit B (RPB2) identified Fusarium isolates as Fusarium verticilloides, Fusarium soloni, Fusarium falciforme and Fusarium oxysporum. According to our knowledge, this study is the first report of the occurrence of Fusarium falciforme causing dry rot on potato tubers in Pakistan. The pathogenicity test confirmed the re-appearance of dry rot symptoms with Fusarium falciforme on potato tuber. The formation of Fusarium falciforme Ag NPs was confirmed using UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Field-emission scanning electron microscopy (FE-SEM) analysis. The synthesized Ag NPs showed color change with Fusarium falciforme and accordingly, UV peak was observed at 431 nm. The XRD revealed Ag based specific angles at 36.14°, 44.26°, 64.42° and 77.44° corresponding to face cubic structure. Similarly, FTIR band absorption at 3297 cm, 1626 cm and 1057 cm ascribed the presence of various biomolecules with O-H, N-H and C-N stretching vibrations based on Ag NPs synthesis. SEM indicated 29 nm synthesized mainly spherical Ag NPs and EDS analysis showed the presence of Ag in NPs. Maximum zone of inhibition with Fusarium falciforme Ag NPs was observed against Pseudomonas aeruginosa, Escherichia coli, Pseudomonas syringae and Staphylococcus aureus at 0.05 LSD significance.