Morphological Characteristics and Genetic Variability of Trichoderma spp. From Conventional Cotton Crop Soils in Federal District, Brazil

This study aimed to characterize 41 isolates of Trichoderma from conventional cotton crops soils as the morphological and cultural characteristics and to investigate polymorphism, using RAPD markers. The most common group comprised 80.6% of the isolates and was identified as a strain of Trichoderma harzianum. The others species were T. aureoviride (7.3%), T. viride (7.3%) and T. crassum (4.8%). The four species were morphologically distinct in the evaluated characteristics such as colony appearance and mycelium growth rate after being grown on malt extract agar (MEA), potato dextrose agar (PDA) and oatmeal agar (OA) media, and also in shape of conidia, phialides, and conidiophores. The four species were separated in a dendogram, after using RAPD markers. Besides, RAPD was efficient in demonstrating the high intraspecific genetic variation among isolates of two species (T. harzianum and T. aureoviride).