Characterization of Fusarium spp. infecting cumin in Bangladesh: Morphological, cultural, pathogenic, and genetic perspectives

Cumin (Cuminum cyminum L.) is a high-value spice crop recently introduced in Bangladesh, where its cultivation is still in the early stages due to limited availability of adapted germplasm and vulnerability to soil-borne diseases. Among these, Fusarium wilt, caused by Fusarium spp., poses a major constraint, leading to significant yield losses in favorable environments. The present study was conducted to characterize the causal agents of cumin wilt in Bangladesh through integrated morphological, cultural, pathogenic, and molecular approaches. Field trials with four advanced cumin lines (CN026, CN028, CN031, and CN038) were conducted across five agro-ecological zones (AEZs) under natural disease pressure. Significant variation in disease incidence and severity was observed among genotypes and locations, with CN026 exhibiting the highest resistance, especially in Bogura. A total of 20 Fusarium isolates were collected from naturally infected plants and characterized based on colony morphology, growth rate, spore morphology, and pathogenicity. ITS-based PCR amplification and sequencing identified five distinct species: F. oxysporum, F. solani, F. chlamydosporum, F. thapsinum, and F. longipes. Phylogenetic analysis confirmed genetic diversity among isolates, with several species reported for the first time in cumin in Bangladesh. Pathogenicity assays showed considerable virulence variability, further validating the need for integrated resistance screening. This study provides the first comprehensive account of Fusarium diversity affecting cumin in Bangladesh and highlights CN026 as a promising line for future breeding and management programs. The findings serve as a critical resource for developing targeted strategies to mitigate cumin wilt and enhance sustainable cumin production in the region.