Molecular identification of endophytes from maize roots and their biocontrol potential against toxigenic fungi of Nigerian maize

Abstract

Plants benefit from plant-associated microorganisms, of which endophytes are of particular interest as they are transmitted from generation to generation. This study characterises endophytes from maize roots and determines their biocontrol potential against toxigenic fungi in Nigerian maize. Maize roots were collected from farms in Lafia, and stored grain samples were collected from the six Northern States of Nigeria, from which endophytes and toxigenic fungal strains were isolated. Molecular identification employing 16SrRNA/internal transcribed spacer (ITS) sequences for isolated fungal endophytes was carried out, and mycotoxins produced by fungi were determined by high-performance liquid chromatography analysis. Biocontrol activity of the endophytes was determined using the dual culture confrontation test. Aspergillus and Fusarium genera were the prevalent isolated fungal species. Eight fungal endophytes were identified of which Trichoderma harzianum, Dichotomopilus erectus and Burkholderia spp. were the isolates with biocontrol activities, while 12 Aspergillus spp. were found to produce varying amounts of ochratoxin A and aflatoxin B1, respectively. T. harzianum showed the best inhibition (74%), followed by D. erectus (50%) and Burkholderia spp. (48%). T. harzianum showed poor inhibition of Aspergillus flavus (B7) at 30%. However, results from the Pakdaman Biological Control Index showed that T. harzianum has the best antifungal biocontrol activity of the three endophytes. The study concludes that antifungal biocontrol agents can be sourced from endophytes to obtain indigenous control activities that can check mycotoxin contamination of food and livestock feed, as well as elucidate possible metabolites for agricultural and industrial applications, which will help improve plant performance, increase crop yield and sustainability.