Incidence and detection of cucurbit mosaic disease in Assam

Abstract

The cucurbits belong to the family Cucurbitaceous (gourd family) under the order Cucurbit ales which include many economically important vegetable and fruit species. Among various factors, viruses are one of the important factors reducing in quantity as well as quality of cucurbits. These crops are severely affected by the cucurbit mosaic disease worldwide, which is the major viral disease of the cucurbits. Considering the importance of the disease, the present investigation was taken up for incidence, detection, host range study and characterization of viruses associated with cucurbit mosaic disease in Assam. Survey was conducted in 5 districts of Assam (Sonitpur, Biswanath, Jorhat, Sivasagar, Dibrugarh) during 2021-22. Symptomatology revealed presence of various mosaic symptoms in the surveyed areas. Among the five surveyed locations, the symptoms observed in Sonitpur district were severe, whereas Biswanath district were moderate and mild symptoms were observed in Jorhat, Sivasagar, and Dibrugarh districts. Vector incidence study showed that aphid is the predominant vector. Molecular assay confirmed the presence of Cucumber Mosaic Virus in the collected cucurbit samples of surveyed areas; with severe incidence of mosaic disease in Sonitpur (90.91%), moderate in Biswanath (66.67%), mild in Jorhat (14.29%), Sivasagar (11%) and Dibrugarh (25%) districts. Molecular characterization of Cucumber mosaic virus cucurbit isolate from Jorhat district of Assam, was done through partial sequencing and similarity analysis showed 90.94 to 94.74 per cent sequence homology with different worldwide isolates of Cucumber mosaic virus.