Characterization of Pythium Species Associated with Root Rot of Cucumber in Greenhouse Production Systems

Abstract

Root rot caused by Pythium species is a major constraint in greenhouse cucumber production, leading to poor seedling establishment, reduced plant vigor, and significant yield losses. Accurate characterization of Pythium species associated with the disease is essential for effective diagnosis and disease management in protected cultivation systems. The present study investigated the morphological and molecular characteristics of Pythium species isolated from cucumber plants exhibiting root rot symptoms in greenhouse production areas. Diseased root samples were collected from affected greenhouses, and pathogen isolation was carried out using selective media and standard microbiological techniques. Morphological characterization included examination of colony growth patterns, hyphal structures, sporangia, oogonia, and oospore formation under laboratory conditions. Due to the close similarity among species, molecular identification was performed using internal transcribed spacer (ITS) region sequencing and phylogenetic analysis to confirm species identity and genetic relationships. The results revealed the occurrence of multiple Pythium species associated with cucumber root rot, with varying levels of pathogenicity and aggressiveness. Pathogenicity assays demonstrated significant differences in disease severity, root discoloration, and seedling mortality among isolates. Environmental conditions commonly prevailing in greenhouse systems, particularly high moisture and humidity, favored pathogen development and disease progression. The integration of morphological and molecular analyses improved the accuracy of species identification and provided comprehensive insights into pathogen diversity within greenhouse cucumber production systems. The findings contribute valuable information for disease monitoring and support the development of integrated management strategies aimed at reducing root rot incidence and improving sustainable cucumber production.