Molecular characterization and in silico analysis of 'secreted in xylem 4' (Six4) gene from Fusarium oxysporum infecting Pisum sativum.

Fusarium oxysporum, a soilborne fungus, causes significant threats to world agriculture through causing vascular wilt in crops such as garden pea (Pisum sativum). This study delved into the Secreted in Xylem 4 (Six4) gene, which plays a function in the pathogenicity of F. oxysporum. For the first time, the complete Six4 gene of F. oxysporum isolate isolated from pea was sequenced, revealing both conserved regions and variations across specialized forms. The pathogenic nature of the isolate was validated by disease severity and progression studies, which demonstrated its virulence and showed that it fulfilled the Koch's postulates. Semi-quantitative PCR confirmed that Six4 is actively expressed in infected garden pea plant. Molecular and phylogenetic investigations of the Six4 gene showed that the isolate shared a monophyletic group with FOSC. The structural modelling of the SIX4 protein, including secondary and tertiary structures, revealed important characteristics such as alpha-helices and beta-sheets, with active binding pockets identified using CASTp while ligand-binding analyses using COACH meta-servers suggested possible interactions with small molecules. This study highlights the possibility of creating eco-friendly chemical agents or inhibitors aimed at this effector protein. These results enhance our knowledge of fungal pathogenicity and will aid in developing future methods to prevent Fusarium wilt in pea and other plants.