Abstract

SOSA, Daynet et al. Genetic diversity determined by its-aflp analysis of Trichoderma spp. in Venezuela. Rev. Protección Veg. [online]. 2014, vol.29, n.1, pp. 42-51. ISSN 1010-2752.

The genetic diversity among 68 Trichoderma isolates from different cultivars, substrates and localities was established by ITS-AFLP analysis. The ribosomal DNA region ITS1-5.8S-ITS2 was sequenced and amplified with the primers ITS1 and ITS4. In the case of AFLP, four oligonucleotide combinations were used. The genetic relationships between isolates were analyzed by the combined use of Principal Component Analysis, Cluster analysis, and the adjustment of an External Logistic Biplot over dissimilarity data using Jaccard, simple coupling, Dice and Rogers, and Tanimoto coefficients. Nine species were identified, and the most abundant were Hypocrea lixii (anamorf Trichoderma harzianum) and T. koningiopsis, with 22 and 20 isolates respectively. They were followed by Hypocrea virens (anamorf T. virens), Trichoderma ghanense; Trichoderma asperellum and Trichoderma brevicompactum, with 7, 6, 4 and 4 isolates, respectively. The least frequent species were Trichoderma erinaceum, Trichoderma spirale and Trichoderma longibrachiatum (2, 1 and 1 isolates, respectively). All the isolates clustered in four AFLP groups, with one containing 99,52% of T. asperellum, and the others with 85,54% and 50% of H. virens and H. lixii, respectively. The other six species grouped together in the four group, and were indistinguishable from one another. The most informative initiator was AG+CAG showing the greatest content of polymorphic information, and which additionally allowed discriminating H. lixii from the other isolates. AG+CAG combination clearly separated T. asperellum from the other species.

Keywords : Trichoderma; ITS; AFLP; polymorphism; biological control.

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