AUTHOR=Morán-Diez María E. , Carrero-Carrón Irene , Rubio M. Belén , Jiménez-Díaz Rafael M. , Monte Enrique , Hermosa Rosa 

TITLE=Transcriptomic Analysis of Trichoderma atroviride Overgrowing Plant-Wilting Verticillium dahliae Reveals the Role of a New M14 Metallocarboxypeptidase CPA1 in Biocontrol

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01120

DOI=10.3389/fmicb.2019.01120

ISSN=1664-302X

ABSTRACT=<p><italic>Verticillium dahliae</italic>, a vascular-colonizing fungus, causes economically important wilt diseases in many crops, including olive trees. <italic>Trichoderma</italic> spp. have demonstrated an effective contribution as biocontrol agents against this pathogen through a variety of mechanisms that may involve direct mycoparasitism and antibiosis. However, molecular aspects underlaying <italic>Trichoderma</italic>–<italic>V. dahliae</italic> interactions are not well known yet due to the few studies in which this pathogen has been used as a target for <italic>Trichoderma</italic>. In the present study, <italic>Trichoderma atroviride</italic> T11 overgrew colonies of <italic>V. dahliae</italic> on agar plates and inhibited growth of highly virulent defoliating (D) <italic>V. dahliae</italic> V-138I through diffusible molecules and volatile organic compounds produced before contact. A <italic>Trichoderma</italic> microarray approach of T11 growing alone (CON), and before contact (NV) or overgrowing (OV) colonies of V-138I, helped to identify 143 genes that differed significantly in their expression level by more than twofold between OV and CON or NV. Functional annotation of these genes indicated a marked up-regulation of hydrolytic, catalytic and transporter activities, and secondary metabolic processes when T11 overgrew V-138I. This transcriptomic analysis identified peptidases as enzymatic activity overrepresented in the OV condition, and the <italic>cpa1</italic> gene encoding a putative carboxypeptidase (ID number 301733) was selected to validate this study. The role of <italic>cpa1</italic> in strain T11 on antagonism of V-138I was analyzed by a <italic>cpa1</italic>-overexpression approach. The increased levels of <italic>cpa1</italic> expression and protease activity in the <italic>cpa1</italic>-overexpressed transformants compared to those in wild-type or transformation control strains were followed by significantly higher antifungal activity against V-138I in <italic>in vitro</italic> assays. The use of <italic>Trichoderma</italic> spp. for the integrated management of plant diseases caused by <italic>V. dahliae</italic> requires a better understanding of the molecular mechanisms underlying this interaction that might provide an increase on its efficiency.</p>