High incidences of yellow mosaic symptoms were observed in soybean and yard-long bean crops in Indonesia in 2009 and in mungbean crops in Vietnam in 2011. All five soybean and 20 yard-long bean samples from Java, Indonesia, and 15 mungbean samples from Vietnam with symptoms tested positive for begomovirus infection by polymerase chain reaction (PCR) with primer pair PAL1v1978B/PAR1c715H. On the basis of collection location and the nucleotide sequence comparisons of the 1.5 kb begomoviral DNA-A components amplified, a subset of samples comprising two soybean and six yard-long bean isolates from Indonesia and five mungbean isolates from Vietnam were taken forward for more detailed examination. Sequence comparison and phylogenetic analysis of the full-length sequences of all Indonesian and Vietnam isolates alongside other legume-infecting begomoviruses revealed that all the isolates from Indonesia were Mungbean yellow mosaic India virus (MYMIV) strain-A, and all from Vietnam were Mungbean yellow mosaic virus (MYMV) strain-B. To the best of our knowledge, this is the first identification of MYMIV and MYMV associated with yellow mosaic of legumes in Indonesia and Vietnam, respectively. The epidemiological implications and potential consequences of the emergence of legume-infecting begomoviruses on legume production in these areas of Southeast Asia are discussed.
Full paper: click here