English abstract
Chili leaf curl virus (ChLCV) and Tomato leaf curl virus (TYLCV) are members of
Genus Begomovirus (family Geminiviridae) which contains single–stranded DNA
viruses transmitted exclusively by the whitefly (Bemisia tabaci). An analysis of the
genetic diversity of begomovirus isolates across Oman was conducted. A total of
twenty five samples were collected from different governorates (Muscat, Musandam,
Ad-Dakhilia, Al-Batinah South, Dhofar and Ash-Sharqiah South) and were tested for
begomovirus, betasatellite and alphasatellite molecules. Rolling circle amplification
(RCA) was used for the detection of full-length begomoviruses, while polymerase
chain reaction (PCR) was used for the detection of betasatellite and alphasatellite. The
complete nucleotide sequence identity of the begomoviruses, alphasatellite and
betasatellite were done in their entirety.
Analysis of these sequences showed that ChLCV and TYLCV are the most prevalent
causal agents of leaf curl disease in Oman and show phylogeographic segregation.
Moreover, ChLCV was characterized from a new weed host Senna italica Miller
located near an infected tomato field. Further it was found that the amplified ChLCV
and TYLCV exhibited the highest nucleotide identity with the previously reported
ChLCV and TYLCV strains infecting tomato in Oman. Although, earlier studies have
indicated that TYLCV is the most prevalent virus infecting mainly tomato crop in
Oman, this study shows that ChLCV has been increasing its host range into diverse
host plants including weeds as well as increasing its distribution into diverse
geographical areas. Furthermore, phylogenetic and other molecular analyses showed
that 88% of tested plant samples with begomovirus-like symptoms were also
associated with tomato leaf curl betasatellite. In addition, the occurrence of
alphasatellite is very rare, and only one okra leaf Oman alphsatellite was also
detected.
