A Leaf Curl Disease in Germplasm of Rapeseed‐Mustard in <scp>I</scp>ndia: Molecular Evidence of a Weed‐Infecting Begomovirus–Betasatellite Complex Emerging in a New Crop

Abstract

Abstract Evaluation of 130 accessions of rapeseed‐mustard germplasm grown at the N ational B ureau of P lant G enetic R esources, N ew D elhi, I ndia during the winter season (2011–2012) revealed the occurrence of a leaf curl disease in seven accessions. The occurrence of the disease was observed in another 62 of 525 accessions evaluated during 2012–2013. The association of a monopartite begomovirus and betasatellite was established with the symptomatic plants by whitefly transmission and PCR amplification. The complete nucleotide sequences of the begomovirus ( JX 270684, 2745 nucleotides), obtained by rolling circle amplification, showed the highest sequence identity (98.1%) with the weed‐infecting begomovirus, C roton yellow vein mosaic virus . Analysis of recombination indicated the probable occurrence of many overlapping inter‐ and intraspecific recombination events. The sequence of betasatellite ( JX 270685, 1355 nucleotides) showed the highest sequence identity (95.7%) with C roton yellow vein mosaic betasatellite . Begomoviruses were not previously known to naturally infect rapeseed‐mustard. This is the first report of the emergence of a weed‐infecting begomovirus–betasatellite complex in rapeseed‐mustard germplasm in India and raises the concern on utilization of such susceptible germplasm in crop improvement programmes.