Detection of cellulase and protease enzyme production by the pathogenic fungus Rhizoctonia solani and evaluation of its virulence in potato

Hussein Subhi Ali Marbat Al-Jubouri, Khalaf Attiya Mohammed Al-Jubouri

Abstract


Rhizoctonia solani is one of the most destructive soil-borne fungal pathogens causing root rot and seedling damping-off in potato crops. The present study aimed to identify and characterize pathogenic isolates of R. solani associated with potato diseases and to evaluate their enzymatic activity and pathogenicity. Four fungal isolates were morphologically and molecularly identified based on colony characteristics, microscopic features, and ITS gene sequencing. The isolates produced typical septate hyphae with right-angled branching and dark sclerotia. PCR amplification generated a 600 bp ITS fragment, and sequence analysis confirmed 99.36% similarity with R. solani. The representative isolate was registered in GenBank under accession number PX247869.1 as R. solani isolate Hus-1. The pathogenic isolates exhibited varying capacities to produce extracellular cellulase and protease enzymes. Isolate R.S1 showed the highest cellulase activity (0.01653 U/mL) and protease activity (19.3833), whereas isolate R.S4 exhibited the lowest enzymatic activity. Pathogenicity tests demonstrated significant variation among isolates in infection percentage, disease severity, and germination reduction. Isolate R.S1 recorded the highest infection rate (62.5%) and disease severity (62.667%), while also causing the lowest tuber germination (33.33%) and cabbage seed germination (16.67%). In contrast, isolate R.S4 showed lower pathogenicity and comparatively higher germination percentages. The findings demonstrated a positive relationship between extracellular enzyme production and fungal virulence. All isolates were pathogenic and capable of producing cell wall-degrading enzymes, particularly cellulase and protease, which contributed to tissue degradation, infection development, and suppression of seed germination.

Keywords


Rhizoctonia solani, Cell wall-degrading enzymes, Cellulase activity, Protease activity, Potato root rot

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References


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DOI: https://doi.org/10.33804/pp.010.03.6098

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