Overexpression of the Trichoderma brevicompactum tri5 Gene: Effect on the Expression of the Trichodermin Biosynthetic Genes and on Tomato Seedlings

Anamariela Tijerino,Javier Moraga,Santiago Gutierrez,Monica G Malmierca,Isidro G Collado,Josefina Aleu,Enrique Monte,Rosa E Cardoza,Rosa Hermosa

doi:10.3390/toxins3091220

Anamariela Tijerino, Javier Moraga + Show 7 more

Open Access

https://doi.org/10.3390/toxins3091220

Copy DOI

Abstract

Trichoderma brevicompactum IBT 40841 produces trichodermin, a trichothecene-type toxin that shares most of the steps of its biosynthesis with harzianum A, another trichothecene produced by several Trichoderma species. The first specific step in the trichothecene biosynthesis is carried out by a terpene cylcase, trichodiene synthase, that catalyzes the conversion of farnesyl pyrophosphate to trichodiene and that is encoded by the tri5 gene. Overexpression of tri5 resulted in increased levels of trichodermin production, but also in an increase in tyrosol and hydroxytyrosol production, two antioxidant compounds that may play a regulatory role in trichothecene biosynthesis, and also in a higher expression of three trichothecene genes, tri4, tri6 and tri10, and of the erg1 gene, which participates in the synthesis of triterpenes. The effect of tri5 overexpression on tomato seedling disease response was also studied.

Highlights

Trichoderma species are well known as biocontrol agents of plant diseases in a broad variety of crops [1], and their ability to produce a huge diversity of antimicrobial compounds and cell wall degrading enzymes has been extensively studied and reviewed [2,3,4,5]
We report the effect of tri5 gene overexpression on the expression of other tri genes in minimal medium and in media containing the antioxidant tyrosol
T. brevicompactum IBT 40841 (=IBT40841) (IBT Culture Collection, Department of Biotechnology, Technical University of Denmarck, Kongens Lyngby, Denmark) wild type strain and three tri5-overexpressing transformants Tb38tri5, Tb40tri5 and Tb41tri5 [13] were used throughout this study

Summary

Introduction

Trichoderma species are well known as biocontrol agents of plant diseases in a broad variety of crops [1], and their ability to produce a huge diversity of antimicrobial compounds and cell wall degrading enzymes has been extensively studied and reviewed [2,3,4,5]. The isomerization of mevalonate produces isopentenyl diphosphate (IPP), which condenses with dimethylallyl diphosphate to produce geranyl diphosphate (GPP), the key precursor of monoterpene biosynthesis. This molecule is condensed again with IPP, affording farnesyl diphosphate (FPP), a common intermediate in the production of: (i) geranylgeranyl diphosphate (GGPP) and its diterpene derivatives; (ii) trichodiene and the subsequent sesquiterpene compounds, including trichothecene fungal toxins; and (iii) squalene, as a precursor of the triterpene pathway to produce prenylated proteins, sterols (ergosterol), ubiquinones, dolichols and other secondary metabolites [6,7] as well as plant carotenoids, gibberellins, tocopherols and chlorophylls [8]

Methods

Results

Discussion

Conclusion