The yellow leaf curl disease of tomato is caused by a complex of virus spec
ies, two of which, tomato yellow leaf curl virus (TYLCV)-Sar and TYLCV-Is,
are involved in epidemics of southern Spain. Plants of Mercurialis ambigua
and Solanum luteum showing abnormal upward leaf curling and leaf distortion
collected in the vicinity of tomato crops were found to be naturally infec
ted with TYLCV-Is and TYLCV-Sar, respectively. These weed species, as well
as Datura stramonium and S. nigrum, which had also been found to be natural
ly infected by TYLCVs in the same region in previous studies, were tested f
or susceptibility to TYLCV-Sar or TYLCV-Is by Agrobacterium tumefaciens-med
iated and by Bemisia tabaci inoculation. Results indicated that both TYLCV-
Sar and TYLCV-Is were able to infect D. stramonium and M. ambigua, whereas
only TYLCV-Sar infected S. nigrum and S. luteum. Implications for the epide
miology of TYLCV are discussed. This is the first report of M.ambigua and S
. luteum as hosts of TYLCV.