NOVEL DEFECTIVE INTERFERING DNAS ASSOCIATED WITH AGERATUM YELLOW VEINGEMINIVIRUS INFECTION OF AGERATUM CONYZOIDES

Defective DNA forms of the geminivirus ageratum yellow vein virus (AYV V) have been identified in naturally infected Ageratum conyzoides plan ts. Several examples of the defective DNA have been cloned from purifi ed virus-specific supercoiled DNA and characterized by sequence analys is. All are approximately half the size of AYVV genomic DNA, and all c ontain intergenic region sequences and the 5' terminus of gene CI as w ell as additional sequences that are unrelated to the viral genomic DN A. The chimeric nature of the defective DNA distinguishes it from prev iously characterized geminivirus defective and satellite DNAs. The def ective DNA ameliorates disease symptoms and causes a significant delay in the accumulation of viral DNA during the early stage of infection when coinoculated with the AYVV genomic DNA into Nicotiana benthamiana , suggesting a biological role as a defective interfering DNA. (C) 199 7 Academic Press.