Molecular Identification of Rhizoctonia solani Isolated from Cucumber (Cucumis sativus L.) and Its Biological Control

Abstract

Abstract At this study, the causative root rot agent was isolate and molecularly identified in cucumber which were grown in Nineveh province, northern of Iraq, in autumn season of 2022. A pathogenic fungus thought to be responsible for Cucumis sativus seedling damping-off disease and root rot. The symptoms of disease are the manifestation from partially yellowing on the leaves of cucumber, seedling damping-off to wilting of plant. Species of fungi isolated of infected plants were further grown on agar in form of potato dextrose which formed aerial mycelia as white to brown. The fungus was identified from the Morphological diagnosis as Rhizoctonia solani, and the pathogen was confirmed by Koch’s hypotheses as well as the results of amplification using the polymerase chain reaction (PCR) and nucleotide sequence analysis using BLAST showed that the R. solani isolate was genetically distinct from the R. solani isolates in the National Centre for Biotechnology Information (NCBI). Moreover, the complete verified ITS sequences are homologous to the isolates of R. solani in GenBank database having 99% similarity. Therefore, it was recorded in Gen Bank under the accession number OQ231503.1. and the results of the plastic tunnel showed that the Trichoderma harizanum T22 led to a significant reduction in the incidence and severity rate of infection recorded 64.17% and 23.500% respectively