Morpho-Molecular Identification and First Report of Trichoderma Aggressivum is Causing Green Rot on White Button Mushroom in Iraq

Abstract

The aim of this study was to morphological isolation and identification of fungus associated with the fruits and culture media of the white mushroom Agaricus bisporus. The results of isolation and identification from the sampling areas included Baghdad, Babylon, and Diwaniyah. Besides, Sulaymaniyah governorates showed the association of seven species of fungi associated the fruiting body and culture media of the white mushroom A. bisporus represented by the two pathogens Cladobotryum spp. and Trichoderma spp. As well as, the competitive fungi of A. bisporus culture medium, such as Aspergillus spp. and Penicillium spp. and Phoma sp. and Rhizopus spp., and Ulocladium sp. The most common pathogenic fungus was Cladobotryum spp. with a frequency of 56.2%, followed by Trichoderma spp., with a frequency of 54.1%, which appeared in samples from two sampling areas. Conversely, species T. aggressivum recorded a frequency of 42.5%, which is the first record in Iraq on the fruits and media of white fungus. The fungus Aspergillus spp. showed the existence percentage reached 65.5%, which is the highest among the competing fungi, followed by Penicillium spp., with an existence percentage of 26.6%. Then, Rhizopus spp., Phoma sp., and Ulocladium sp. with a frequency of 16.6%, 10.4%, and 10.4%, respectively. The results of the pathogenicity of the fungus isolate Trichoderma spp. indicated that all the isolates tested for the pathogenicity of the fruiting bodies of the white mushroom A. bisporus led to the infection of the fruiting bodies and their transformation into brown color and damage. The isolates of the fungus T. aggressivum (isolate 1 and isolate 2) recorded a disease severity of 60.0% and 60.0%, respectively. While, at a temperature of 4 °C, the isolates of the fungus T. aggressivum (1 and 2) recorded a disease severity amounted to 40.0% and 50.0%, respectively, compared to the control treatment without fungus, where the disease severity amounted to 0.0%. The results of the molecular identification of the DNA of the T. aggressivum, which showed the highest pathogenicity of A. bisporus fruiting bodies, using the specialized primer ITSI/ITS4, as it gave bands with a molecular weight of 600 bp. These findings were compared with the GenBank with a high similarity for the fungus T. aggressivum and it has been deposited in the Gen Bank with the accession number (OQ109172).