Biodiversity of the genus Trichoderma and identification of marker genes
involved in the antagonism between Trichoderma spp. and plant pathogenic
fungi
As Mediterranean islands are known for their high diversity of vascular plants and a high
level of endemism, they can provide basic insights into the relationship between
geographical patterns and ecological processes. Studying the soil fungus
Trichoderma/Hypocrea is of special interest to our working group due to its world-wide
distribution, the continuos ongoing identification of new isolates, and its high percentage of
strains being effective as biocontrol agents.
We isolated 482 strains of Hypocrea/Trichoderma from 15 soils comprising undisturbed
and disturbed soil environments. Isolates were identified at the species level by the
oligonucleotide BarCode for Hypocrea/Trichoderma, sequence similarity analysis and
phylogenetic inferences. The majority of the isolates were positively identified as pan-
European and/or pan-global Hypocrea/Trichoderma species from Sections Trichoderma
and Pachybasium.
T. harzianum (H. lixii) is well known as a biocontrol agent against a range of
economically important plant pathogens. In the present study we used a Rapid Subtraction
Hybridisation approach to isolate genes which are differentially expressed during mycelial
contact between T. harzianum and R. solani, and could serve as marker genes for
selection of superior biocontrol strains. The 50 characterised clones comprised proteins
involved (i) in protein synthesis and turn-over, (ii) in metabolism, and (iii) in the hydrolysis
of macromolecules. An acetyl xylane esterase and an endoglucanase showed significant
upregulation during in vivo confrontation of a T. harzianum strain with high antagonistic
capability towards R. solani, while the expression was low or absent in a T. harzianum
strain with poor antagonistic activity
