Cultural and molecular characterizations of some isolates of Trichoderma spp.

Abstract EN

Cultural and molecular characterizations were carried out on a collection of 18 isolates of Trichoderma spp.

belonging to the three antagonistic species T.

atroviride P.

Karsten, T.

harzianum Rifai and T.

longibrachiatum Rifai.

Differences about the growth rate and colony characterization including time of first appearance of green conidia, the presence of yellow pigmentation of young conidia, the presence of diffusing pigment in the agar, odour and colony appearance were recorded among Trichoderma spp.

on PDA and SNA media.

Displayed intra-specific variability related to the previous characters remains within the limit of each species and the growth curve of Trichoderma spp.

isolates was distinctive of species on PDA medium.

Molecular characterization by RAPD with 3 OPA primers and the mini-satellite M13 generated 247 bands, and cluster analysis of the RAPD data set resulted in two principal clusters.

The first cluster is subdivided in two principal sub-clusters, where the first sub-cluster corresponds to the species T.

longibrachiatum with a value percentage similarity among isolates ranged from 31 to 100 %, and the second to the species T.

harzianum with a percentage of similarity which varies between 42.

1 and 87.5 %.

Cluster II corresponds to the species T.

atroviride with a percentage of similarity ranged between 33.3 and 40 %, thus displaying an intra-specific genetic diversity.

Primers OPA1, OPA10 and OPA17 generated RAPD marker bands for T.

longibrachiatum and T.

atroviride species.