Co-expression of two genes, a chitinase (chit42) and proteinase (prb1), implicated in mycoparasitism byTrichoderma hamatum

Abstract

Mycoparasitism of fungal plant pathogens by Trichoderma species is a complex process that involves the production and co-ordinated secretion of cell-wall degrading enzymes. Genes implicated in mycoparasitism by Trichoderma atroviride contain motifs in the promoter region, designated MYRE1-MYRE4, that are proposed to act as binding sites for a global inducer of the mycoparasitic response. The aim of our study was to establish whether these motifs also were present in Trichoderma hamatum and whether the presence of these motifs could predict co-expression when T. hamatum was confronted by a pathogen. Using a combination of targeted, degenerate and inverse PCR, homologues of the mycoparasitismrelated genes ech42 (chit42), prb1 and lam1.3 (xbg1.3-110), which encode an endochitinase, proteinase, and ␤-1,3-glucanase, respectively, were cloned and sequenced from T. hamatum. Alignment of the promoter regions of the three genes revealed identical regions in the chit42 and prb1 promoters, which were 6-9 base pairs in length and conserved in position. Specifically, the regulator y motifs MYRE1-MYRE4 were fully conserved, together with a fifth motif, identified by this research. A substrate assay designed to investigate the response of these genes from T. harzianum and T. hamatum to a simple carbon source (glycerol) showed that, in contrast to chit42 and prb1, xbg1.3-110 was not expressed. Further comparison of the expression patterns of these three genes between T. harzianum and T. hamatum using the glycerol substrate assay showed that no Accepted for publication May 27, 2004. 1 Corresponding author. E-mail: steyaej1@lincoln.ac.nz chit42 or prb1 expression could be detected in T. harzianum when it was grown under the same conditions as T. hamatum. This showed that the response of these genes to glycerol was species specific and that a single expression pattern for these genes was not common to all Trichoderma species. Confrontation assays were used to investigate the response of the three T. hamatum genes to the more complex substrate posed by the fungal pathogen Sclerotinia sclerotiorum. Once again gene expression analysis showed that both chit42 and prb1 were co-expressed and moderately induced during confrontation against Sclerotinia sclerotiorum. Although xbg1.3-110 previously had been implicated in mycoparasitism by T. harzianum, this study detected no xbg1.3-110 expression during confrontation between T. hamatum and S. sclerotiorum. These findings show that the MYRE1-MYRE4 together with MYRE5 are present in two species of Trichoderma, T. atroviride and T. hamatum and that the presence of these motifs could predict coexpression in response to two carbon sources.

Tvbgn3, a β-1,6-Glucanase from the Biocontrol Fungus Trichoderma virens , Is Involved in Mycoparasitism and Control of Pythium ultimum

“…The described gene expression pattern is consistent with the regulatory motifs found in the Tvbgn3 promoter region. No cis-acting elements involved in carbon or nitrogen regulation were found, yet several MYRE elements, proposed to be involved in mycoparasitism (7,55), were identified. Recently, Montero et al (39) described a similar pattern of expression for another ␤-1,6-glucanase (Bgn16.3) purified from T. harzianum.…”

Aspergillus fumigatusexoβ(1‐3)glucanases family GH55 are essential for conidial cell wall morphogenesis

“…A graphical representation of the phylogenetic relationships between members of GH55 family, including 43 proteins of 21 filamentous fungi ( Figure 1 and Table S3), showed the existence of at least six subfamilies with a bootstrap value of 99-100%: AfExg5p, AfExg6p, and AfExg8p group unambiguously into three different subfamily composed of exoβ(1-3)glucanases. AfExg5p grouped with TaTag83, ThLam1.3, and TaXbg1.3 (Bara, Lima, & Ulhoa, 2003;Cohen-Kupiec, Broglie, Friesem, Broglie, & Chet, 1999;Steyaert, Stewart, Jaspers, Carpenter, & Ridgway, 2004), the characterised exoβ(1-3)glucanases…”

MrpacC regulates sporulation, insect cuticle penetration and immune evasion in Metarhizium robertsii

“…Deletion of PacC homologues reduced fungal virulence in plant pathogens Fusarium oxysporum (Caracuel et al, 2003a) and Magnaporthe oryzae (Landraud et al, 2013), mammalian pathogens Aspergillus fumigatus (Bignell et al, 2005), Candida albicans (Davis, 2009) and Cryptococcus neoformans (Trushina et al, 2013), as well as the mycoparasitic fungi Trichoderma harzianum (Moreno-Mateos et al, 2007) and Trichoderma virens (Trushina et al, 2013). Besides regulating pH adaptation, PacC transcription factor is also known to control fungal cell wall remodelling (Nobile et al, 2008;Trushina et al, 2013) and the expression of chitinases (Steyaert et al, 2004;Trushina et al, 2013), pectate lyases (Kramer-Haimovich et al, 2006) and production of secondary metabolites (Merhej et al, 2011). In addition, many fungal genes that respond to salt stress or metal toxicity are also controlled by the PacC transcription factor (Caracuel et al, 2003b;Cherrad et al, 2012).…”