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Identification of stable sources of resistance to mungbean yellow mosaic virus (MYMV) disease in mungbean [Vigna radiata (L.) Wilczek]

Nagaraj,, Basavaraj, S, Padmaja, A.S., Nagaraju, N, Ramesh, S
Plant genetic resources 2019 v.17 no.4 pp. 362-370
Mungbean yellow mosaic virus, Vigna radiata, carrier state, catechol oxidase, coat proteins, cultivars, enzyme activity, genotype, greenhouses, mung beans, peroxidase, phenols, phenylalanine ammonia-lyase, polymerase chain reaction
Yellow mosaic disease (YMD) caused by mungbean yellow mosaic virus (MYMV) is one of the most destructive biotic production constraints in mungbean. Development and introduction of resistant cultivars are considered as the most economical and eco-friendly option to manage YMD, for which availability of stable sources of resistance is a pre-requisite. A set of 14 mungbean genotypes including a susceptible check were evaluated for responses to YMD under natural infection across three seasons and under challenged inoculation in glasshouse for one season. None of the genotypes were immune to YMD and produced different degrees of response to MYMV in terms of yellow mosaic symptoms (YMS). Based on the delayed appearance of initial YMS, and lower estimates of per cent disease index and area under disease progressive curve (AUDPC) in response to natural infection and challenged inoculation, five genotypes namely AVMU 1698, AVMU 1699, AVMU 16100, AVMU 16101 and KPS 2 were identified as resistant to YMD. Failure of detection of MYMV through polymerase chain reaction (PCR) using MYMV coat protein gene-specific primer and successful detection of the same through rolling circle amplification-PCR suggested latent infection of MYMV in resistant genotypes. The resistance response of the five genotypes could be attributed to enhanced activities of enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia lyase and increased concentration of total phenols. These results are discussed in relation to strategies to breed mungbean for resistance to YMD.