Molecular Characterization of Tomato Yellow Leaf Curl Virus (TYLCV) Infecting Pepper and Common Bean

摘要

Background: Tomato Yellow Leaf Curl Virus (TYLCV) is a circular single strand DNA begomovirus, which causes one of the most important diseases in tomato worldwide. This virus was observed on tomato plants for first time in Saudi Arabia in 1978 and has been endemic since then. Materials and Methods: Plant samples of pepper ( Capsicum frutescens ) and common bean (showing leaf yellowing and curling) were collected from Jizan and Hail Southwest and North of Saudi Arabia, respectively. Rolling Circle Amplification (RCA) was used to amplify the complete genome for two TYLCV strains (TYLCV-GB and TYLCV-Pep). The amplified complete genomes of TYLCV-GB (2779 bp) and TYLCV-Pep (2764 bp) were cloned, sequenced and registered in the GenBank database under accession numbers KF444467 and KF435136, respectively. Results: Phylogenetic analyses revealed that the length of the Intergenic Region (IR) was 305 bp for TYLCV-GB and 290 bp for TYLCV-Pep. The homology tree showed that TYLCV-GB and TYLCV-Pep belong to two different clusters and the identity between them was 81.2%. The TYLCV-GB clustered with isolates from Sudan, whereas TYLCV-Pep clustered with isolates from Iran. Six Open Reading Frames (ORFs) (V1, V2, C1, C2, C3 and C4) were found on the TYLCV-Pep dsDNA replicative form while seven ORFs (V1, V2, C1, C2, C3, C4 and C5) were found on the TYLCV-GB genome. The DNA β satellite was found to be associated with TYLCV-GB but not with the TYLCV-Pep. Conclusion: This study provide definitive evidence based on molecular data suggesting that TYLCV-GB and TYLCV-Pep are two different strains in Saudi Arabia with different invasion routes.