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

Siddhartha N Borah,Suresh Deka,Swaranjit S Cameotra,Debahuti Goswami,Hridip K Sarma

doi:10.3389/fmicb.2016.01505

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.

Highlights

Fusarium verticillioides (Sacc.) Nirenberg is genetically the most intensively studied species in Fusarium section Liseola (Jurgenson et al, 2002)
The Fourier transform infrared spectroscopy (FTIR) spectrum (Figure 2A) of the biosurfactant sample, produced by P. aeruginosa SS14 grown in the medium containing glucose as carbon source was found to be similar to that of the standard RL R-95 thereby confirming the biosurfactant to be rhamnolipid
The biosurfactant used in this study was produced by P. aeruginosa SS14 using glucose as the sole carbon source and was characterized to be mono-rhamnolipid with two constituent congeners by FTIR and Liquid chromatography mass spectrometry (LC-MS) analyses

Summary

Introduction

Fusarium verticillioides (Sacc.) Nirenberg (teleomorph Gibberella moniliformis Wineland) is genetically the most intensively studied species in Fusarium section Liseola (Jurgenson et al, 2002). This fungus is primarily a pathogen of maize (Zea mays L.) that causes stalk and ear rot, but has been reported to cause disease in other crops like sorghum (Palmero et al, 2012). Fumonisins have been implicated in oesophageal cancer in humans and subsequently several carcinogenicity mechanisms have been proposed (Rheeder et al, 1992; Howard et al, 2001) They have been associated with disruption of sphingolipid metabolism and folate transport and described as a potential risk factor for human neural tube defects (Marasas et al, 2004). The prevention of colonization of F. verticillioides in maize has occupied a thrust area in food safety research

Methods

Results

Conclusion