Mungbean Yellow Mosaic India and Bean Common Mosaicviruses Induced Severe Epidemic of Yellowing and Mosaic Vein Banding Diseases, Respectively, on Yardlong Bean in Bali, Indonesia

Abstract

Outbreak of yellowing and mosaic vein banding diseases emerged simultaneously during 2013 in the main yardlong bean (Vigna unguiculata sub sp. Sesquipedalis L.) growing regions of Bali, Indonesia. Mosaic disease was characterized by mosaic pale green with vein banding  on the leaves and could simply be distinguished from yellowing disease symptoms in which bright yellow mosaic was much more pronounced. Reverse transcription or/and polymerase chain reaction (PCR) using primers specific to genus Begomovirus and Potyvirus successfully amplified an expected DNA band if subjected to total nucleotide derived from yellowing and mosaic vein banding leaves respectively, but not vice versa. Pairwise comparison of sequences obtained from PCR products with corresponding nucleotide sequences in the Gen Bank confirmed the association of Mungbean yellow mosaic India virus (MYMIV) with yellowing and Bean common mosaic virus strain Blackeye cowpea mosaic virus (BCMV-BlCMV) with mosaic vein banding diseases. Nucleotide sequence analyses of MYMIV or BCMV-BlCMV isolates from the bean showed high sequence identities (more than 95%) and phylogeneticaly clustered with respective virus isolates from Java. This report provide first evidence of MYMIV and BlCMV infections in yardlong bean from Bali region of Indonesia.

Keywords: Begomovirus, disease outbreak, identification, nucleotide sequence, Potyvirus.