Species diversity of indigenous Trichoderma from alkaline pistachio soils in Iran

The diversity of Trichoderma spp. was investigated in alkaline soils of pistachio orchards at different geographic areas in Kerman province, Iran. A total of 161 Trichoderma isolates were obtained and identified at the species level by their morphological characters and sequence analysis of their internal transcribed spacer (ITS) and tef1-α genomic regions. Totally, five species of Trichoderma were identified, including T. harzianum, Trichoderma sp., T. virens, T. brevicompactum and T. longibrachiatum. ITS nucleotide sequences could not find molecular differences between T. harzianum and Trichoderma sp. To identify and differentiate these two species, the sequences of the translation-elongation factor 1-α (tef1-int 4 (large)) were determined for five representative isolates of T. harzianum and Trichoderma sp. The TrichoBLAST similarity search using the tef1-α sequences of the T. harzianum and Trichoderma sp. isolates determined in this study, revealed as T. harzianum. However, there was 34 nucleotides difference in tef1-α sequences, between the two groups of isolates. According to the results, more than 80% of the isolates belonged to two species T. harzianum and Trichoderma sp. T. harzianum was introduced as the dominant species in soil of pistachio orchards. Logistic regression analysis showed no relationship between the soil properties (pH, EC) and presence of Trichoderma spp. (R2 = 0.26, Pr = 0.74, 0.26 > 0.05).