Molecular Identification of Ditylenchus dipsaci Infesting Garlic Bulbs and Its Pathogenic Effect on Plant Growth

Abstract

Molecular identification of Ditylenchus dipsaci infesting garlic bulbs and its pathogenic effects on plant growth were investigated to confirm species identity and assess disease impact under controlled conditions. Garlic bulb samples showing typical symptoms such as swelling, tissue softening, and distortion were collected from infected fields, and nematodes were extracted using standard extraction techniques. Morphological observations were complemented with molecular analysis using PCR amplification and sequencing of rDNA ITS regions to confirm species-level identification. Phylogenetic analysis validated the identity of D. dipsaci populations and revealed low intraspecific variation among isolates collected from different locations. Pathogenicity assays were conducted under greenhouse conditions by inoculating healthy garlic plants with nematode suspensions, and growth parameters including plant height, bulb weight, root development, and biomass reduction were recorded. Results indicated significant suppression of plant growth in inoculated plants compared to controls, with severe reduction in bulb formation and overall vigor. Nematode infection led to tissue necrosis, stunted growth, and reduced nutrient uptake, demonstrating its strong parasitic impact on garlic. The study highlights the high virulence and adaptability of D. dipsaci in garlic production systems and confirms its role as a major limiting factor in yield. Integrated use of molecular diagnostics and pathogenicity assessment provides a reliable framework for early detection and management of this economically important nematode in allium crops.