Molecular detection and comparative sensitivity analysis of diagnostic assays for Cucumber mosaic virus infecting cucumber

Résumé fourni par la source

Cucumber mosaic virus (CMV) is a globally important plant virus with an exceptionally broad host range, causing severe yield losses in cucurbit crops. Sensitive and rapid detection is essential for effective disease monitoring, particularly under conditions of low viral titre and mixed infections. To address this, field surveys were conducted in major cucumber-growing regions of Kolar district, Karnataka, India and ten symptomatic leaf samples were collected. Koch’s postulates were confirmed in cucumber and tobacco through mechanical transmission. Molecular characterisation using coat protein (CP) gene-specific primers confirmed all isolates as CMV subgroup IB, exhibiting > 99 % nucleotide identity. A representative isolate was used to develop and evaluate the analytical sensitivity of four molecular diagnostic methods—conventional reverse transcription-polymerase chain reaction (RT-PCR), loop-mediated isothermal amplification (LAMP), quantitative real-time PCR (qPCR) and reverse transcription recombinase polymerase amplification (RT-RPA). Ten-fold serial dilutions of cDNA were employed to assess detection limits. BcaBEST LAMP showed the highest sensitivity, detecting CMV down to 10 zeptogram (zg), while qPCR consistently detected at attogram-to-zeptogram levels. Reverse transcription recombinase polymerase amplification and conventional RT-PCR detected up to 1 femtogram (fg) and 1 picogram (pg) respectively. Both LAMP and qPCR exhibited rapid, specific and reproducible amplification. This study establishes a practical framework for selecting suitable detection platforms to strengthen CMV surveillance, seed health testing and disease management programmes.

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