Identification of alternate weed hosts of mungbean yellow mosaic India virus

Yellow mosaic, one of the devastating diseases of pulse crops, particularly of mungbean and urdbean is known to reduce the yield significantly. The disease is caused by several begomoviruses that persist in volunteer crop plants or alternate weed hosts during the absence of their primary hosts. The objective of this study was to identify the alternate weed hosts of the mungbean yellow mosaic India virus (MYMIV), a begomovirus associated with yellow mosaic disease (YMD) of mungbean and urdbean, in-and-around Kanpur using PCR assays. Leaf samples from 22 weed plants growing in-and-around mungbean and urdbean crop fields at the research farms of the ICAR-Indian Institute of Pulses Research, Kanpur were collected during Kharif 2023 for PCR-based detection of MYMIV using species-specific primers targeting the coat protein (CP) gene. In the PCR assays, a MYMIV-specific amplicon was detected in seven weed plants, namely Phyllanthus urinaria, Achyranthes aspera, Lepidium didymium, Convolvulus arvensis, Breynia disticha, Fumaria vaillantii, and Anagallis arvensis. The presence of MYMIV was further confirmed through sequencing and BLAST analysis of the CP gene amplicon in these weeds. This study constitutes the first report supporting the role of these seven weeds belonging to the families Convolvulaceae, Phyllanthaceae, Papaveraceae, Primulaceae, Brassicaceae, and Amaranthaceae, as potential natural reservoirs of MYMIV. Removal of host weeds may therefore be advocated as one of the activities of integrated management of MYMIV-induced YMD in susceptible pulse crops such as mungbean and urdbean.