Molecular Identification And Phylogenetic Analysis Of Trichoderma Isolates Obtained From Woody Plants Of The Semi-Arid Of Northeast Brazil

The objective of this study was to perform the molecular identification and phylogenetic analysis of 19 Trichoderma isolates, obtained from surface-disinfected leaves of forest species, in a Cerrado-Caatinga ecotone, in the semiarid region of Northeast Brazil. The DNA regions studied in the experiment were the genes for the translation elongation factor (tef1) and the second largest RNA polymerase subunit (rpb2). The sequences of each gene and the concatenated ones (tef1 + rpb2) were aligned with those of the most similar Trichoderma isolates available in GenBank for the construction of phylogenetic trees. The sequences obtained from the two studied gene regions allowed the identification of 14 isolates within three species of Trichoderma (T. orientale - seven isolates; T. koningiopsis - six isolates and T. longibrachiatum - one isolate) and for five isolates, it was not possible to identify them at the species level. In some cases, the PCR success rate was sufficient for only one of both genes, or both genes were not sufficient for resolution of the species, or hitherto undescribed species were involved. This is the first report of these fungal species in woody forest plants from four botanical families: Fabaceae (Bauhinia cheilantha, Cenostigma macrophyllum, Diptychandra aurantiaca, Mimosa tenuiflora and Pityrocarpa moniliformis), Myrtaceae (Myrcia tomentosa), Combretaceae (Combretum glaucocarpum and Combretum laxum) and Boraginaceae (Cordia toqueve). The high occurrence of native Trichoderma isolates reveals the potential for mycological studies in plants from the semiarid region of Northeast Brazil. In spite of our limited data, comparison with the literature indicated that in the investigated area T. orientale may show a preference towards leaf substrates compared to twigs, that T. longibrachiatum may be more commonly associated with Fabaceae than with other plants, whereas T. koningiopsis is a widespread unspecific species with a broad range of plant substrates.