Identification of novel sources of yellow vein mosaic disease resistance in okra (Abelmoschus esculentus L. Moench)

The yellow vein mosaic disease (YVMD) transmitted through whitefly is a serious threat to okra fruit and quality production. Although, the disease can be managed up to some extent through chemicals by controlling the vector population. But, the use of resistant varieties is most economic and environment friendly. Therefore, the present study was planned to find out the new resistant source through artificial screening against YVMD. For this, the sixteen accessions belonging to seven different okra wild species along with two cultivars of cultivated okra (Pusa Sawani and Punjab Padmini) were evaluated against YVMD during rainy season of 2016 and 2017. Screening against YVMD was conducted using viruliferous whitefly (Bemisa tabaci Genn.) mediated mass inoculation and observations were recorded from symptomless to very severe infection. Observations were recorded consecutively for two years that confirmed no symptoms of YVMD up to 90 Days After Inoculation (DAI) for accession SBT-12597 and SBT-12592 of Hibiscus acutetus resulting zero coefficient of infection (CI) termed as highly resistant. Accessions IC-203833 and IC-470751 of A. angulosus depicting lowest CI value of 2.3 and 3.7 respectively were also assigned as highly resistant to YVMD at 90 DAI. The accession EC-329394 of A. manihot recorded CI value of 67.9 followed by accession IC-141056 (CI 61.6) of A. moschatus and A. tuberculatus (CI = 44.4) were found susceptible to YVMD up to 90 DAI. The cultivated okra A. esculentus variety Pusa Sawani with CI value of 75.0 and Punjab Padmani (CI 60.0) showed highly susceptible and susceptible reaction to YVMD, respectively. Deng universal primer confirmed the resistance in all the selected plants by showing absence of viral DNA.