Specific Aim 3: Determine the impact of a reservoir host on CMB diversity
The ancestors of modern CMBs likely existed in indigenous plants in Africa and moved into cassava when it arrived on the continent. This exchange continues today as whiteflies move between cassava and reservoir plants, and it is likely to impact CMB evolution because the viral populations are under different selective pressures in cassava fields vs. the non-crop reservoir. Analysis of other begomovirus pathosystems has led to two views of the reservoir and viral diversity. One view is that reservoir hosts, which are genetically more variable, harbor more viral diversity, whereas crop hosts select for fewer variants. Alternatively, the genetic variability of the plant host does not affect viral sequence variability and, instead, viral diversity is an intrinsic property of a virus. To examine the role of the reservoir in CMB evolution, we will screen several reservoir species to identify one that can be colonized by B. tabaci SSA1 sub-clade 1 established on cassava (Aim 1) and used to compare CMB evolution during whitefly transmission between reservoir and cassava plants. Our experiments will provide insight into whether propagation of CMBs in the reservoir and their movement to cassava impact diversity over time or if CMB diversity is an intrinsic property.