Nucleotide sequence evidence for the occurrence of three distinct whitefly-transmitted geminiviruses in cassava

• Published in: Journal of general virology Vol. 74; no. 11; pp. 2437 - 2443
• Main Authors: Hong, Y. G, Robinson, D. J, Harrison, B. D
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.11.1993; Society for General Microbiology
• Subjects: Agronomy. Soil science and plant productions; Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Capsid - genetics; DNA, Viral - genetics; Fundamental and applied biological sciences. Psychology; Geminiviridae - classification; Geminiviridae - genetics; geminivirus; Genome, Viral; Insecta - microbiology; Manihot - microbiology; Molecular Sequence Data; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Sequence Homology; Systematics. Structure, properties and multiplication. Genetics; Virus; Genome organization; Vegetable crop; Plant pathogen; Nucleotide sequence; DNA; Geminivirus; Comparative study
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-74-11-2437

1 Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA and 2 Department of Biological Sciences, University of Dundee, Dundee DD1 4HN, U.K. The complete nucleotide sequence of the DNA of Indian cassava mosaic virus (ICMV) and a key part of that of a group B isolate of African cassava mosaic virus from Malawi (ACMV-M) were determined and compared at the nucleotide and encoded amino acid levels with the published sequences of an ACMV group A isolate (ACMV-K) and other whitefly-transmitted geminiviruses (WTGs). The DNA of ICMV consists of two circular single-stranded molecules, DNA-A [2815 nucleotides (nt)] and DNA-B (2645 nt), which differ substantially in sequence from the genome components of ACMV-K (DNA-A 70%, DNA-B 47% sequence identity) and other WTGs. ICMV DNA-A contains eight open reading frames (ORFs) encoding proteins of > 100 amino acid residues, of which four ORFs (one genome sense, three complementary sense) are comparable to those of other WTGs. DNA-B contains one ORF in each sense, as in other WTGs. None of the putative viral proteins are more similar in amino acid sequence to the proteins of ACMV-K than to those of another WTG. The coat protein of ACMV-M is more like that of tomato yellow leaf curl virus from Sardinia (86% sequence identity) than those of ICMV or ACMV-K. The intergenic regions of ACMV-K, ACMV-M and ICMV DNAs differ in size, and largely in sequence, except for two 30 to 40 nt sequences which are also conserved in other WTGs and can form stem—loop structures. The intergenic region of ICMV DNA contains three copies of a 41 nt sequence, and that of ACMV-M DNA contains an imperfect repeat of a 34 nt sequence which resembles the repeated sequence in ICMV DNA. The differences between ACMV-K, ACMV-M and ICMV are considered great enough to justify their separation as isolates of three distinct WTGs: African cassava mosaic virus, East African cassava mosaic virus and Indian cassava mosaic virus. Received 15 April 1993; accepted 12 July 1993.