doi:10.1038/nindia.2012.26 Published online 22 February 2012
Biologists have identified, for the first time, two distinct plant pathogens (begomoviruses) and their associated betasatellite DNA — a circular, single-stranded DNA molecule — causing the deadly leaf curl disease of radish in India.
Whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops, especially in tropical and sub-tropical regions. New begomoviruses are evolving due to mutation, pseudo-recombination and recombination.
The researchers worked on leaf curl disease-infected radish plants in Varanasi and Pataudi region of northern India. They found that the disease was being caused by a complex of two old world begomoviruses and their associated betasatellites. The Varanasi strain was identified as a new recombinant species, radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-[Bangladesh:2] while the Pataudi strain was found to be an isolate of Croton yellow vein mosaic virus-[India] (CYVMV-IN) sharing 95.8% nucleotide identity.
They also found the Varanasi strain to have a hybrid genome, a putative recombinant between euphorbia leaf curl virus and papaya leaf curl virus.
The researchers studied the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses. Both the tomato-infecting begomoviruses showed contrasting and differential interaction with DNA satellites.
The researchers observed evidence of lateral movement of weed infecting begomovirus in the cultivated crops. Their study suggests that the exchange of betasatellites with other begomoviruses could create a new disease complex posing a serious threat to crop production.
The authors of this work are from: Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi and School of Life Sciences, Central University of Gujarat, Gandhinagar, India.