Molecular characterization of a novel defective DNA isolated from tobacco tissues infected with tobacco leaf curl virus

Defective DNA of tobacco leaf curl virus (TLCV) was identified in TLCV-infe cted tobacco plants. The defective DNA was cloned and sequenced. The sequen ce showed it was about half the size of the TLCV DNA-A, and was derived fro m TLCV DNA-A by a large deletion. The defective DNA contained the intergeni c region and part of the AC I (Rep) gene of TLCV, and also novel open readi ng frames (ORFs). The immunotrapping tests showed the defective DNA was ass ociated with geminate particles, suggesting it could be encapsidated in vir us particles. it was transmitted, along with full-length DNA-A, to tobacco plants by grafting and whitefly (Bemisia tabaci).