Fungal entomopathogens as endophytes reduce several species of Fusarium causing crown and root rot in sweet pepper (Capsicum annuum L.)

Abstract

Fusarium Crown and Root Rot (FCRR) is one of the most widespread and economically important diseases caused by a complex of Fusarium spp. infecting a wide crop range worldwide. Although there are many studies on the efficacy of bacterial and fungal biocontrol agents against FCRR, there have been no attempts to investigate the efficacy of entomopathogenic fungi as endophytes for FCRR biocontrol. At the same time, the antagonistic activity of endophytic fungal entomopathogens against plant pathogens remains understudied compared to their well-known biocontrol activity against insect pests. Therefore, the present study was initiated to examine for the first time the antagonistic activity of the fungal entomopathogens Beauveria bassiana (strain NATURALIS) and Metarhizium brunneum (strain BIPESCO5) against three Fusarium species (F. oxysporum, F. culmorum, and F. moniliforme) causing FCRR in vitro through dual-culture tests and in planta following the endophytic establishment of fungal entomopathogens in pot-culture experiments. Both fungal entomopathogens significantly inhibited all Fusarium species in vitro, with competition for niche or resources and antibiosis as modes of action. Further in planta bioassays showed that plants endophytically colonized with fungal entomopathogens had significantly reduced FCRR incidence and severity as well as improved growth, irrespective of fungal entomopathogen or Fusarium spp. This study demonstrates for the first time the biocontrol potential of endophytic fungal entomopathogens against several Fusarium species causing FCRR. It is also the first report for the suppressive activity of M. brunneum as an endophyte against plant pathogens.