Figure 1 (Right) Typical geminiviruses consist of two joined quasi-isometric subunits, with a characteristic “waist” constriction, and pointed ends: purified particles of the species Maize streak virus (MSV) stained with uranyl acetate. The bar represents 50 nm. (Left) Capsids are constructed as shown: triangles superimposed on negatively-stained virion indicate organisation of capsomers. Micrographs: K. Kasdorf.
Figure 2 Typical genomic organization of mastreviruses. ORFs are denoted as either being encoded on the virion (V) or complementary (C) strand, and corresponding genes are indicated. The positions of the stem-loop containing the conserved TAATATTAC sequence and the encapsidated, complementary sense primer-like molecule (small arrow) are shown. Introns (open boxes) are shown in the RepA/RepB and MP genes. Shaded boxes indicate large intergenic region (LIR) and short intergenic region (SIR).
Figure 3 Genomic organization of curtoviruses. ORFs are denoted as either being encoded on the virion (V) or complementary (C) strand. Gene designations are shown where these are known. The C3 ORF is not present in Horseradish curly top virus (HrCTV). The position of the stem-loop containing the conserved nonanucleotide sequence (TAATATTAC) is shown. CP, coat protein; Rep, replication-associated protein; REn, replication enhancer.
Figure 4 Typical genomic organization of begomoviruses. ORFs are denoted as either being encoded on the virion (V) or complementary (C) strand, preceded by component designation if bipartite (top). The CP is encoded by the AV1 ORF. The position of the stem-loop containing the conserved TAATATTAC sequence is shown. The “common region” (CRA and CRB, top) of sequence shared between the two genomic components, or the “intergenic region” (IR, bottom) are shown (gray boxes). TrAP, transcriptional activator protein; Rep, replication-associated protein; REn, replication enhancer; MP, movement protein; NSP, nuclear shuttle protein. The AV2 ORF is not present in New World begomoviruses.
Figure 5 Neighbour-joining dendrogram of sequence relationships among members of the family Geminiviridae. The whole-sequence and component A alignments and dendrogram were produced using DNAMAN 3.0 (Lynnon BioSoft, Quebec, Canada) for Windows 95, which uses a CLUSTAL-type algorithm. Horizontal distances are proportional to sequence distances; vertical distances are arbitrary. The dendrogram was bootstrapped 1000 times (percent scores shown at nodes), and rooted on an arbitrary sequence. Taxonomic divisions are shown alongside. “New World” and “Old World” refer to geographic origins of species of begomoviruses.
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