Asymptomatic populus alba: a tree serving as a reservoir of begomoviruses and associated satellites.

Populus alba (P. alba) is a widespread tree species. An analysis of five mature P. alba, two from Quetta (Balochistan province) and three from Faisalabad (Punjab province) Pakistan, showed all to be infected by the monopartite begomovirus Tomato leaf curl Kerala virus (ToLCuKeV) and the alphasatellite Ageratum enation alphasatellite. Additionally, one P. alba was found to be infected with another monopartite begomovirus, Papaya leaf curl virus (PaLCuV), two with cotton leaf curl Multan alphasatellite and three with cotton leaf curl Multan betasatellite. Analysis of the sequences of full-length clones of each component showed them unchanged from published sequences and closely related to isolates identified in hosts other than P. alba, except for the PaLCuV isolate which proved to be a new strain of the virus. A Southern blot analysis showed replication of ToLCuKeV in P. alba ruling out the findings being due to contamination. This is the first report of the infection of mature P. alba trees by begomoviruses in association with satellites. The significance of these findings are discussed. [ABSTRACT FROM AUTHOR]