Exploring the possibilities of enhancing enzymatic activities of phytopathogenic fungi for their utility in biological control of waterhyacinth

Abstract

Global infestation of invasive hydrophyte waterhyacinth [Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae)], has led to an intensive investigation of several methods for its control. Among the most eco-friendly methods implemented, several phytopathogenic fungi are often found to cause damage to their host-plants tissue, through production of phytotoxic metabolites that induce disease symptoms (such as chlorosis, necrosis, etc.), eventually leading to the death of the plants and in the case of weeds, their control. Newline During this study many fungal cultures were isolated from waterhyacinth. 152 fungal isolates, belonging to more than 25 genera were identified by morphological studies. Several potential isolates were subjected to molecular characterization by Sanger sequencing using 18S rDNA. They were evaluated for their biocontrol potential and host-range studies. Among the potential fungal pathogens of waterhyacinth, few have shown to produce an array of lytic, cell-wall-degrading enzymes (CWDEs) that can degrade the polysaccharides of plant cell walls and break the structural moiety of the plants. On the basis of the damage intensity incurred by the primary metabolites on the host weed, the present study highlights on one of the first reports, where xylanases (in its optimised condition), with a molecular weight of 24 kDa, produced by Fusarium oxysporum sp. lycopersici 4287, have shown potency against its targeted host, waterhyacinth (a noxious aquatic weed) by aiming the xylans, which are a major hemicellulosic component of the cell walls. Evolutionary diversion of the responsible enzyme-producing genes (XYL2, XYL3, XYL5) among related species of the selected fungi, also gives an idea of perception of the involvement of these genes in cell-wall degradation. The knowledge of the mode of action with their evolutionary significance eventually helps to predict the breaking of the structural rigidity and moiety of the plant and leading to control its invasiveness, via close relatedness.