The Trichoderma harzianum demon: complex speciation history resulting in coexistence of hypothetical biological species, recent agamospecies and numerous relict lineages

Abstract

BackgroundThe mitosporic fungus Trichoderma harzianum (Hypocrea, Ascomycota, Hypocreales, Hypocreaceae) is an ubiquitous species in the environment with some strains commercially exploited for the biological control of plant pathogenic fungi. Although T. harzianum is asexual (or anamorphic), its sexual stage (or teleomorph) has been described as Hypocrea lixii. Since recombination would be an important issue for the efficacy of an agent of the biological control in the field, we investigated the phylogenetic structure of the species.ResultsUsing DNA sequence data from three unlinked loci for each of 93 strains collected worldwide, we detected a complex speciation process revealing overlapping reproductively isolated biological species, recent agamospecies and numerous relict lineages with unresolved phylogenetic positions. Genealogical concordance and recombination analyses confirm the existence of two genetically isolated agamospecies including T. harzianum sensu stricto and two hypothetical holomorphic species related to but different from H. lixii. The exact phylogenetic position of the majority of strains was not resolved and therefore attributed to a diverse network of recombining strains conventionally called 'pseudoharzianum matrix'. Since H. lixii and T. harzianum are evidently genetically isolated, the anamorph - teleomorph combination comprising H. lixii/T. harzianum in one holomorph must be rejected in favor of two separate species.ConclusionsOur data illustrate a complex speciation within H. lixii - T. harzianum species group, which is based on coexistence and interaction of organisms with different evolutionary histories and on the absence of strict genetic borders between them.

Novel Endophytic Trichoderma spp. Isolated from Healthy Coffea arabica Roots are Capable of Controlling Coffee Tracheomycosis

“…The next majority of strains (18) were identified as members of the Harzianum-Catoptron Clade [37]. The phylogenetic analysis of tef1 locus revealed that seven strains formed a separated clade inside of -T. harzianum species complex‖ (H. ‗pseudoharzianum' sensu Druzhinina et al [36]), possessing a unique tef1 allele ( Figure 1B), that was not detected in rhizosphere of C. arabica [19].…”

Optimization of solid-state fermentation conditions for Trichoderma harzianum using an orthogonal test

“…Trichoderma harzianum T S1 belongs to the deuteromycetes Amon, Trichosporon Gang, Trichosporon mesh, sticky spore fungi (Druzhinina et al, 2010) and is widely used as a seed treatment to control disease, promote growth, and increase plant yield (Mastouri et al, 2010;Druzhinina et al, 2010). This fungus releases cell wall-degrading enzymes, which combat plant pathogens through a variety of mechanisms (Ghisalbert and Sivasithamparam, 1991;Monte, 2001;Monteiro et al, 2010).…”

New isolates of Trichoderma antagonistic to Sclerotinia sclerotiorum

“…Following the classification of Druzhinina et al (2010), we observed some ITS sequence variation among the isolates clustering with T. harzianum. The formation of subgroups within T. harzianum is recognized, since it is regarded as a species complex (Kullnig et al 2000).…”

“…With the development of molecular phylogeny, the genus Trichoderma has been grouped into taxonomic sections (Bissett 1984); based on phylogenetic clades (Druzhinina et al 2010). As an extension of this work, Druzhinina and colleagues (2005) developed a DNA barcode for molecular identification of Trichoderma species, called TrichOKEY.…”

“…The current taxonomy of Trichoderma is based mainly on molecular analysis (Druzhinina et al 2010, Kullning et al 2000, since morphological identification of the anamorph forms are unreliable . With the development of molecular phylogeny, the genus Trichoderma has been grouped into taxonomic sections (Bissett 1984); based on phylogenetic clades (Druzhinina et al 2010).…”