LAUSR

A complex of begomoviruses and their associated DNA-satellites is causing leaf curl diseases in Asia, Africa and the Mediterranean Region. Begomoviruses and DNA-satellites native to Asia and Africa are distinct from each other. Different combinations of geographically distinct monopartite begomoviruses, betasatellites and an alphasatellite were analyzed in infection experiments: cotton leaf curl Kokhran virus (CLCuKoV) and cotton leaf curl Multan virus (CLCuMuV) from Pakistan along with their associated cotton leaf curl Multan betasatellite (CLCuMuB); okra yellow crinkle virus (OYCrV), cotton leaf curl Gezira betasatellite (CLCuGeB), ageratum leaf curl Cameroon betasatellite (ALCCMB) and ageratum leaf curl Cameroon alphasatellite (ALCCMA) from Cameroon; tomato yellow leaf curl virus (TYLCV) from the Mediterranean Region. The infectivity assays were carried out in the model host species Nicotiana benthamiana and agro-infectious clones containing partial tandem repeats of the begomovirus and satellite genomes. The tested begomoviruses from different regions could functionally interact with non-cognate betasatellites and alphasatellite. Plants co-inoculated with CLCuKoV/CLCuGeB or CLCuMuV/CLCuGeB developed, for both combinations, more severe symptoms than with the begomovirus alone and the infection was verified by Southern blot hybridization. Nonetheless, CLCuKoV and CLCuMuV were shown also to support infection by ALCCMB, whereas OYCrV and TYLCV were able to support infection with CLCuMuB, ALCCMB and CLCuGeB. Moreover, all begomoviruses from different geographical origins supported ALCCMA from Africa. The results confirm that geographically diverse begomoviruses can functionally interact with non-cognate DNA-satellites, which may cause the emergence of new begomovirus-satellite complexes. Possibly, exchange of DNA-satellites may occur across continents leading to the emergence of new viral diseases.