Rhamnolipid Biosurfactant against Fusarium verticillioides to Control Stalk and Ear Rot Disease of Maize

Abstract

Antifungal activity of rhamnolipids (RLs) has been widely studied against many plant pathogenic fungi, but not against Fusarium verticillioides, a major pathogen of maize (Zea mays L.). F. verticillioides causes stalk and ear rot of maize or asymptomatically colonizes the plant and ears resulting in moderate to heavy crop loss throughout the world. F. verticillioides produces fumonisin mycotoxins, reported carcinogens, which makes the contaminated ears unsuitable for consumption. In this study, the RL produced using glucose as sole carbon source was characterized by FTIR and LCMS analyses and its antifungal activity against F. verticillioides was evaluated in vitro on maize stalks and seeds. Further, the effect of RL on the mycelia of F. verticillioides was investigated by scanning electron microscopy which revealed visible damage to the mycelial structure as compared to control samples. In planta, treatment of maize seeds with a RL concentration of 50 mg l-1 resulted in improved biomass and fruiting compared to those of healthy control plants and complete suppression of characteristic disease symptoms and colonization of maize by F. verticillioides. The study highlights the potential of RLs to be used for an effective biocontrol strategy against colonization of maize plant by F. verticillioides.

Efficacy of a rhamnolipid biosurfactant to inhibit Trichophyton rubrum in vitro and in a mice model of dermatophytosis

“…The superior activity of the standard RL, R‐95, against spores in comparison with the test RL could be a result of the higher purity of R‐95 (95%) and also a differential congener composition of both the RLs leading to differential antimicrobial activity . However, the activity of a RL also varies from pathogen to pathogen depending on its interaction with the target organism, as in our previous study involving the same RL against the phytopathogen, Fusarium verticillioides , the activity was higher in case of the test RL as compared to R‐95 which was in contrast to what has been observed in the present study . RLs have structures and properties similar to that of detergents and have been reported to intercalate into the membrane phospholipid bilayer, thereby facilitating the permeability of the membrane and flow of metabolites.…”

“…The crude rhamnolipid was then purified by silica gel column chromatography . The determination of chemical structure (Figure ) of the purified RL by ATR‐FTIR and LC‐ESI‐MS analyses has been reported earlier …”

“…Inhibition of the mycelial growth of T. rubrum was screened according to Borah et al Sabouraud dextrose agar (SDA) media containing RL at final concentrations of 50, 100, 200, 400 and 500 μg/mL were prepared and poured into 90‐mm Petri plates after sterilization. Control plates were prepared with SDA without RL.…”

Microbial biosurfactants: current trends and applications in agricultural and biomedical industries

“…) against phytopathogens including Botrytis cinerea and that of rhamnolipids (Borah et al . ) against Fusarium verticillioides a major pathogen of maize. In addition, rhamnolipids have shown potential as biopesticides (Soltani Dashtbozorg et al .…”

“…More recently the potential of biosurfactants in seed protection and growth stimulation have been investigated, showing the effectiveness of LPs (Toral et al 2018) against phytopathogens including Botrytis cinerea and that of rhamnolipids (Borah et al 2016) against Fusarium verticillioides a major pathogen of maize. In addition, rhamnolipids have shown potential as biopesticides (Soltani Dashtbozorg et al 2016), fungicides (Shah et al 2005) and as antizoospore agents (Miao et al 2015).…”