title: Ageratum enation virus-a begomovirus of weeds with the potential to infect crops.
abstract: Samples of two Ageratum conyzoides, one Sonchus oleraceus and one turnip (Brassica rapa var. rapa) exhibiting virus-like symptoms were collected from Pakistan and Nepal. Full-length begomovirus clones were obtained from the four plant samples and betasatellite clones from three of these. The begomovirus sequences were shown to be isolates of Ageratum enation virus (AEV) with greater than 89.1% nucleotide sequence identity to the 26 AEV sequences available in the databases. The three betasatellite sequences were shown to be isolates of Ageratum yellow leaf curl betasatellite (AYLCB) with greater than 90% identity to the 18 AYLCB sequences available in the databases. The AEV sequences were shown to fall into two distinct strains, for which the names Nepal (consisting of isolates from Nepal, India, and Pakistan-including the isolates identified here) and India (isolates occurring only in India) strains are proposed. For the clones obtained from two AEV isolates, with their AYLCB, infectivity was shown by Agrobacterium-mediated inoculation to Nicotiana benthamiana, N. tabacum, Solanum lycopersicon and A. conyzoides. N. benthamiana plants infected with AEV alone or betasatellite alone showed no symptoms. N. benthamiana plants infected with AEV with its associated betasatellite showed leaf curl symptoms. The findings show that AEV is predominantly a virus of weeds that has the capacity to infect crops. AYLCB appears to be the common partner betasatellite of AEV and is associated with diseases with a range of very different symptoms in the same plant species. The inability to satisfy Koch's postulates with the cloned components of isolate SOL in A. conyzoides suggests that the etiology may be more complex than a single virus with a single betasatellite.
authors: Plant Biotechnology Department, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Sector H-12, Islamabad 44000, Pakistan. gullsbs@outlook.com.
authors: Muhammad
authors: M
authors: Tahir
authors: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad 38000, Pakistan. imranamin1@yahoo.com.
authors: Imran
authors: I
authors: Amin
authors: School of Biological Sciences, University of the Punjab, New Campus, Lahore 54590, Pakistan. haider65us@yahoo.com.
authors: Muhammad Saleem
authors: MS
authors: Haider
authors: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad 38000, Pakistan. shahidmansoor7@gmail.com.
authors: Shahid
authors: S
authors: Mansoor
authors: Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Jhang Road, Faisalabad 38000, Pakistan. rob.briddon@gmail.com.
authors: Rob W
authors: RW
authors: Briddon
mesh_terms: D053839:Begomovirus / Q000145:classification / Q000235:genetics*; D003001:Cloning, Molecular; D019295:Computational Biology / Q000379:methods; D018556:Crops, Agricultural / Q000821:virology*; D016679:Genome, Viral; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D057685:Plant Weeds / Q000821:virology*; D017422:Sequence Analysis, DNA