Arch Virol (2005) 150: 1003–1012
Evidence for interspeciﬁc-recombination for three
monopartite begomoviral genomes associated with
the tomato leaf curl disease from central Sudan
A. M. Idris and J. K. Brown
Department of Plant Sciences, The University of Arizona, Tucson, Arizona, U.S.A.
Received September 28, 2004; accepted December 6, 2004
Published online February 10, 2005
Summary. Two distinct viral genotypes were identiﬁed in the same tomato plant
collected from Gezira, Sudan and are provisionally designated Tomato leaf curl
Sudan virus (ToLCSDV-Gez) and Tomato yellow leaf curl virus-Sudan (TYLCV-
SD). A third genotype was identiﬁed in tomato samples collected in Shambat,
Sudan (ToLCSDV-Sha). The ToLCSDV-Gez and ToLCSDV-Sha isolates were
∼90% identical, TYLCV-SD from Gezira shared ∼93% identity with TYLCV-
Mld. Recombination analyses identiﬁed two fragments in the ToLCSDV-Gez and
TYLCV-SD genomes, providing evidence that these two genomes had undergone
intermolecular recombination. A half unit size (737 nt) single-stranded satellite
DNA was associated with ToLCSDV-Gez and TYLCV-SD.
The Gezira region of Sudan is the largest irrigated agricultural production area
in the country, owing to its proximity to the Nile River. Tomato is cultivated as a
minor crop during the summer and as a major crop throughout the winter season,
which begins in November. In both seasons, tomato is produced primarily for
the domestic market . The winter cultivation of tomato coincides with the
seasonal population increase of the whiteﬂy Bemisia tabaci (Genn) [10, 13, 25],
whereas in the summer, vector populations are typically quite low.
Tomato leaf curl disease (ToLCD), which was ﬁrst reported in 1932 as a
serious disease of tomato in Gezira, Sudan by Cowland , is still the most
important limiting factor to tomato production in central Sudan, at times resulting
in a 75% yield reduction. Symptoms of the disease include foliar curling and
yellow mottling, stunting of plants, and reduced fruit set .