Diversity of Trichoderma species in chili rhizosphere that promote vigor and antagonism against virulent Phytophthora capsici

Abstract

The oomycete Phytophthora capsici causes chili pepper (Capsicum annuum L.) blight that is extremely hard to control. In this work, the diversity of Trichoderma species from chili farms and their antagonistic activity against virulent strains of P. capsici were studied. The maximum likelihood phylogenetic analysis based on translation elongation factor 1α (TEF1α) locus revealed divergent evolution in the population structure of Trichoderma species exhibiting antagonistic activities against P. capsici. In vitro confrontation analysis revealed that Trichoderma harzianum, T. viride and T. reesei displayed over 85.5% inhibition of mycelial growth of P. capsici. Furthermore, soil application of Trichoderma species under greenhouse conditions effectively suppressed root–rot severity by 11.24–26.50% (P < 0.05) hallmarked by a significant improvement in mean fresh weights (P = 3.57E-31, F = 486.98, P < 0.05) and length of the roots (P = 3.76E-28, F = 313.51, P < 0.05) compared to controls harboring P. capsici, not inoculated with Trichoderma. We provide evidence of genetic diversity of beneficial Trichoderma species in chili farms having both biocontrol potential against P. capsici coupled with growth promoting properties for chili roots.