single complementary-sense transcript of a geminiviral DNA beta satellite is determinant of pathogenicity

• Published in: Molecular plant-microbe interactions Vol. 18; no. 1; pp. 7 - 14
• Main Authors: Saeed, M, Behjatnia, S.A.A, Mansoor, S, Zafar, Y, Hasnain, S, Rezaian, M.A
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 2005; The American Phytopathological Society
• Subjects: Amino Acid Sequence; amino acid sequences; Base Sequence; Begomovirus; Biological and medical sciences; Cauliflower mosaic virus; circular DNA; Cotton leaf curl virus; DNA, Satellite - genetics; DNA, Viral - genetics; Fundamental and applied biological sciences. Psychology; Geminiviridae; Geminiviridae - genetics; Geminiviridae - pathogenicity; Geminivirus; gene expression; Gossypium - virology; Molecular Sequence Data; Mutation; Nicotiana - genetics; Nicotiana tabacum; nucleotide sequences; Open Reading Frames - physiology; phenotypic variation; Phytopathology. Animal pests. Plant and forest protection; plant morphology; plant viruses; Plants, Genetically Modified; RNA, Messenger; RNA, Viral; satellite DNA; single-stranded DNA; tobacco; Tomato leaf curl virus; transgenic plants; viral DNA; Pakistan; Satellite DNA; Pathogenicity; Plant; Messenger RNA; Microbiology; Geminiviridae; Begomovirus; gene expression
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-18-0007

Small circular single-stranded DNA satellites, termed DNAbeta, have recently been found associated with some geminivirus infections. The DNA beta associated with Cotton leaf curl virus is responsible for symptom expression of a devastating disease in Pakistan. Mutagenesis of DNA beta revealed that the complementary-sense open reading frame (ORF) betaC1 is required for inducing disease symptoms in Nicotiana tabacum. An ORF present on the virion-sense strand betaV1 appeared to have no role in pathogenesis. Tobacco plants transformed with a betaC1 ORF under the control of the Cauliflower mosaic virus 35S promoter or with a dimeric DNA beta exhibited severe disease-like phenotypes, while plants transformed with a mutated version of betaC1 appeared normal. Northern blot analysis of RNA from the transgenic plants, using strand-specific probes, identified a single complementary-sense transcript. The transcript carries the full betaC1 ORF encoding a 118-amino acid product. It maps to the DNA beta at nucleotide position 186 to 563 and contains a polyadenylation signal 18 nt upstream of the stop codon. A TATA box is located 43 nt upstream of the start codon. Our results indicate that betaC1 protein is responsible for DNA beta-induced disease symptoms.