Biotic, molecular, and phylogenetic characterization of bean calico mosaicvirus, a distinct Begomovirus species with affiliation in the squash leaf curl virus cluster

Bean calico mosaic virus (BCMoV), a whitefly-transmitted geminivirus from S onora, Mexico, was purified, and the genome components were cloned and sequ enced. Purified viral fractions and cloned genome components were infectiou s by biolistic inoculation to bean, completing Koch's postulates for both. The B biotype of the whitefly Bemisia tnbaci efficiently transmitted both n ative virus and progeny virus derived from cloned DNA inoculum. Host ranges of native virus and of progeny virus derived from cloned DNA were identica l based upon whitefly and biolistic mediated transmission, respectively. BC MoV has a relatively wide experimental host range among begomoviruses known to infect bean, encompassing genera and species within the Fabaceae, Malva ceae, and Solanaceae. BCMoV has a bipartite genome, as do other New World b egomoviruses. BCMoV DNA-A shared highest nucleotide sequence identities wit h squash leaf curl virus-E strain (SLCV-E) and cabbage leaf curl virus (CaL CV) at 80.1 and 80.7%, respectively. BCMoV DNA-B shared highest nucleotide sequence identity with SLCV-E at 70.7%. The common region (CR) sequences of BCMoV and SLCV-E are 73 to 76% identical; however, modular cis-acting elem ents within the CR involved in replication origin function and recognition are 100% conserved. Phylogenetic analysis indicated that BCMoV DNA-A shares a most recent common ancestor with the DNA-A of two viruses that also occu r in the Sonoran Desert, SLCV-E and Texas pepper virus (TPV-TAM), and CaLCV from Florida. In contrast, a phylogenetic analysis indicated that BCMoV DN A-B shares a most recent common ancestor with SLCV-E; whereas DNA-B of CaLC V clustered in a separate clade with pepper hausteco virus. Collectively, b iological and molecular characteristics indicate that BCMoV is a distinct b egomovirus species with the northernmost distribution of any begomovirus is olated from bean in the Americas. Furthermore, the phylogenetic relationshi ps of begomovirus cognate components are not necessarily identical, suggest ing that DNA-A and DNA-B of some begomoviruses may have different evolution ary histories.