Abstract

Sponge gourd (Luffa cylindrica) is an economically important vegetable crop cultivated throughout  India and this crop is severely affected by yellow mosaic disease caused by begomovirus. In this study, an attempt was made to transmit the begomovirus by sap. The causal agent was easily transmitted by sap to ridge gourd, sponge gourd andNicotiana benthamiana. Several factors affecting the efficient sap transmission of causal virus was identified. Use of two antioxidant (sodium sulphite and β-mercaptoethanol) and two abrasive (celite and corborundum) and application of inoculum on first true leaves and cotyledons by rubbing with cotton swab, dipped in inoculum resulted in significant higher rate of transmission. The sap inoculation protocol resulted in variable percentage of infected plants from different factors like buffer combinations, source of inoculum, age of inoculum, genotypes of test plants, and species of plants, temperature, seasons and organic materials. The most susceptible growth stage of ridge gourd plant to sap inoculation was seven days old seedlings that produced 100% infection. The sap transmission was confirmed by coat protein gene polymerase chain reaction (PCR) amplification, cloning and sequencing from infected plants. Sap transmission of begomovirus infecting luffa has not been reported previously in India.

Key words: Sap transmission, begomovirus, Tomato leaf curl New Delhi virus(ToLCNDV), cucurbits.