Geminivirus disease complexes: the threat is spreading.

Symptom-modulating DNA satellites associated with geminiviruses have come to our attention only recently but have proven to be widespread, associated with many diseases throughout the Old World, and economically significant, particularly in developing countries. Recent developments are elucidating the role played by these novel molecules in pathogenicity and in overcoming host plant defense. Further investigation into the promiscuous nature of these satellites and their ability to recruit further begomoviruses indicates that regions not yet affected by such begomovirus-satellite complexes are at great risk.