Molecular Characterization of a Strain of Squash Leaf Curl China Virus from the Philippines

The complete nucleotide sequence of infectious cloned DNA components (A and B) of the causal agent of squash leaf curl disease in the Philippines was determined. DNA-A and DNA-B comprise 2739 and 2705 nucleotides, respectively; the common region is 174 bases in length. Five ORFs were found in DNA-A and two in DNA-B. Partial dimeric clones containing DNA-A and DNA-B, constructed in a binaryvector and transformed into Agrobacterium tumefaciens, induced systemic infection in agro-inoculated pumpkin plants (Cucurbita moschata). The total DNA-A sequence was most closelyrelated to that of Squash leaf curl China virus (SLCCNV) (88% identity), although the existence of B component of SLCCNV has not been reported. The deduced coat protein was like that of SLCCNV (98% amino acid sequence identity) and the Philippines virus has low sequence identityto Squash leaf curl virus (SLCV) and Squash mild leaf curl virus (SMLCV) (63 and 64% total nucleotide sequence identities, respectively). From these results, we propose that the Philippines virus be designated Squash leaf curl China virus-[Philippines] (SLCCNV- [PH