MOLECULAR CONFIRMATION OF ToLCNDV RESISTANCE IN CUCUMBER THROUGH AGROINOCULATION AND FIELD SCREENING

Viral diseases, especially ToLCNDV causes serious threat to cucumber cultivation in India and many other countries of the world.Screenings for resistance to ToLCNDV in cucumber were elucidated in the current work for the first time under natural epiphytotic (RBD with three replications) as well by artificial screening (CRD with three replications) through agro-inoculation.Specific DNA-A primers were used in PCR amplification as it is a bipartite virus.Among the four cucumber genotypes studied, mean percent disease index and incidence ranged from 0.00 to 92.00% and 0.00 to 93.3% in 2023 and 2024 respectively.Under natural epiphytotic conditions, the genotype DC 70 was found to be free from ToLCNDV infection while DC 773 recorded 75.00 PDI and 87.50% disease incidence and DC 769 with 42.85 PDI and 71.42% disease incidence in 2023 while DC 70 and P-85 were found to be free from ToLCNDV infection and DC 773 recorded 65.71 PDI and 85.00% disease incidence and DC 769 with 40.00 PDI and 75.00% disease incidence in 2024.In artificial screening, the genotype DC 70 was found to be free from ToLCNDV infection followed by P-85 with 22.91 PDI and 46.60% disease incidence (inoculated)and 9.20 PDI and 6.66% disease incidence (control)while DC 773 recorded 92.00 PDI and 93.3%disease incidence (inoculated) and 22.40 PDI and 40.00%disease incidence(control).Out of the four genotypes screened, DC 70 showed a durable immune reaction and the resistant source identified is a good candidate for theresistant breeding programmes for ToLCNDV in cucumber.