Pathogenicity and Molecular Identification of Aphanomyces euteiches Causing Root Rot of Pea in Waterlogged Soils

Abstract

Pea (Pisum sativum L.) is an important legume crop cultivated worldwide for its nutritional and economic value; however, its productivity is severely affected by soil-borne diseases, particularly under poorly drained and waterlogged soil conditions. Root rot caused by Aphanomyces euteiches is considered one of the most destructive diseases of pea, resulting in root discoloration, tissue decay, wilting, stunted growth, and substantial yield losses. The present study was conducted to investigate the pathogenicity and molecular identification of A. euteiches associated with pea root rot in waterlogged agricultural soils. Diseased pea plants exhibiting typical root rot symptoms were collected from affected fields, and pathogen isolation was performed using selective culture techniques. Morphological characterization was conducted based on colony appearance, hyphal growth, and reproductive structures, while molecular identification was carried out using polymerase chain reaction (PCR) amplification and sequencing of conserved genomic regions. Pathogenicity assays were performed under controlled greenhouse conditions by inoculating healthy pea seedlings with representative isolates to confirm disease development and evaluate virulence levels. The results confirmed the consistent association of A. euteiches with symptomatic pea roots collected from waterlogged fields. Inoculated plants developed characteristic root rot symptoms, including extensive root necrosis, reduced root biomass, chlorosis, and plant wilting, thereby fulfilling Koch’s postulates. Molecular sequence analysis revealed high genetic similarity between the obtained isolates and previously reported A. euteiches strains from legume-growing regions worldwide. Environmental conditions associated with excessive soil moisture were found to favor pathogen development and disease severity. The findings provide important insights into the pathogenic behavior and molecular identity of A. euteiches in pea production systems affected by waterlogging stress. Early detection and accurate pathogen identification are essential for implementing effective disease management strategies, including improved drainage practices, resistant cultivars, and integrated soil health management to minimize crop losses in pea cultivation.