Ulrich Melcher is a molecular biologist who has become fascinated by the molecular evolution of viruses of plants. The studies performed by him and his collaborators have led to several major hypotheses that are being further considered. The group believes that the number of known viruses is only a small fraction of viruses existing in the world, that some virus species have coexisted with their plant hosts as long as recognizable plants have existed. These views lead to the ideas that viruses are not necessarily pathogens and that viruses are important components of ecosystem. The group is also interested in untangling the relationships among viruses, their hosts, and other organisms also associated with the plants. His mentors included plant biochemist Joe Varner, molecular biologist Kjeld Marcker and immunologist Jonathan Uhr.