Department of Disease and Stress Biology, John Innes Centre, Colney Lane, Norwich, NR4 7UH, UK
Accepted: 10 May 2005
The Ipomoea-infecting begomoviruses are an evolutionary
curiosity. Two such viruses have been identified: Sweet potato leaf
curl virus (SPLCV; Lotrakul & Valverde, 1999) and Sweet
potato leaf curl Georgia virus (SPLCGV); originating from the USA
(SPLCV and SPLCGV) and Spain (SPLCV-Ipo; previously known as Ipomoea
yellow vein virus (Banks et al., 1999) but now recognised as
a distinct strain of SPLCV). These viruses are monopartite (no DNA B or
DNA β component has been identified for any of the viruses), have a
genome organisation typical of Old World begomoviruses and are distinct
from all other begomoviruses.
Cuttings of Ipomoea indica (Convolvulaceae) showing yellow
vein symptoms (Fig. 1) were collected in the vicinity of Catania, Sicily
in 1999. A full-length clone of the begomovirus associated with the
disease was produced by PCR-mediated amplification with a pair of
primers abutting at their 5' ends and spanning (for SPLCV-Ipo)
nucleotides 697-758 (virion-sense primer
5'-GGATCCGCTGAACTTTGGCCAGATCTTCACTATG-3', complementary-sense primer
5'-GGATCCTTATTGGGCCTTGTATCACGAATCAACC-3'). These were designed to the
sequence of SPLCV-Ipo (accession number AJ132548) and span a unique BamHI
restriction endonuclease site. The full-length PCR product was cloned
into the T-Easy vector (Promega) and the sequence of a single clone was
determined. This sequence (accession no. AJ586885) is 2830 nucleotides
in length and shows the arrangement of genes typical of the genomes (or
DNA A components) of Old World begomoviruses. The virus is closely
related to other begomoviruses isolated from Ipomoea spp.
including SPLCGV (84.2% nucleotide sequence identity), SPLCV (89.9%) andSPLCV-Ipo (90.9%), with which it clusters in phylogenetic analyses
(Fig. 2). We conclude that the isolate originating from Sicily is a
strain of SPLCV which we provisionally designate SPLCV-[Sicily]. The
occurrence of this begomovirus species in Sicily indicates that its
geographical range extends further across the Mediterranean basin than
previously identified.
+Figure 1: Foliar symptoms of Ipomoea indica naturally infected with SPLCV-[Sicily]
Figure 1: Foliar symptoms of Ipomoea indica naturally infected with SPLCV-[Sicily]
+Figure 2: Neighbour-joining phylogenetic dendrogram based upon an alignment (produced with Clustal X) of the complete nucleotide sequences of Ipomoea-infecting begomoviruses and selected other begomoviruses (or begomovirus DNA A components). Bootstrap confidence values (1000 replicates) are indicated at nodes. Ipomoea-infecting begomoviruses are highlighted in green. SPLCV-[Sicily] is highlighted in orange. The clustering of begomoviruses into those originating from the Old World or New World is labelled. The tree was rooted on the sequence of the distantly-related Maize streak virus (genus Mastrevirus). The other viruses used in the analysis were: Abutilon mosaic virus (AbMV), African cassava mosaic virus (ACMV), Ageratum enation virus (AEV),Ageratum yellow vein virus (AYVV), Beet curly top virus (BCTV; genus Curtovirus), Chili leaf curl virus (ChiLCV), Cotton leaf curl Gezira virus (CLCuGV), Cotton leaf crumple virus (CLCrV), Cotton leaf curl Alabad virus (CLCuAV), Cotton leaf curl Multan virus (CLCuMV), Cotton leaf curl Kokhran virus (CLCuKV), Hollyhock leaf crumple virus (HLCrV), Honeysuckle yellow vein mosaic virus (HYVMV), Indian cassava mosaic virus (ICMV), Mungbean yellow mosaic India virus (MYMIV), Pepper leaf curl virus (PepLCV), Potato yellow mosaic virus (PYMV), Rhynchosia golden mosaic virus (RhGMV), Squash leaf curl virus (SLCV), Sweet potato leaf curl virus (SPLCV), Tobacco leaf curl Japan virus (TbLCJV), Tomato golden mosaic virus (TGMV), Tomato leaf curl Bangalore virus (ToLCBV), Tomato leaf curl Bangladesh virus (ToLCBDV), Tomato leaf curl Karnataka virus (ToLCKV), Tomato leaf curl New Delhi virus (ToLCNDV), Tomato leaf curl Laos virus (ToLCLV), Tomato leaf curl Malaysia virus (ToLCMV), Tomato mottle virus (TMoV), Tomato yellow leaf curl virus (TYLCV), Tomato yellow leaf curl Sardinia virus (TYLCSV) and Watermelon chlorotic stunt virus (WCSV). Species/strain designation follows accepted conventions. Database sequence accession numbers are indicated.
Figure 2: Neighbour-joining phylogenetic dendrogram based upon an alignment (produced with Clustal X) of the complete nucleotide sequences of Ipomoea-infecting begomoviruses and selected other begomoviruses (or begomovirus DNA A components). Bootstrap confidence values (1000 replicates) are indicated at nodes. Ipomoea-infecting begomoviruses are highlighted in green. SPLCV-[Sicily] is highlighted in orange. The clustering of begomoviruses into those originating from the Old World or New World is labelled. The tree was rooted on the sequence of the distantly-related Maize streak virus (genus Mastrevirus). The other viruses used in the analysis were: Abutilon mosaic virus (AbMV), African cassava mosaic virus (ACMV), Ageratum enation virus (AEV),Ageratum yellow vein virus (AYVV), Beet curly top virus (BCTV; genus Curtovirus), Chili leaf curl virus (ChiLCV), Cotton leaf curl Gezira virus (CLCuGV), Cotton leaf crumple virus (CLCrV), Cotton leaf curl Alabad virus (CLCuAV), Cotton leaf curl Multan virus (CLCuMV), Cotton leaf curl Kokhran virus (CLCuKV), Hollyhock leaf crumple virus (HLCrV), Honeysuckle yellow vein mosaic virus (HYVMV), Indian cassava mosaic virus (ICMV), Mungbean yellow mosaic India virus (MYMIV), Pepper leaf curl virus (PepLCV), Potato yellow mosaic virus (PYMV), Rhynchosia golden mosaic virus (RhGMV), Squash leaf curl virus (SLCV), Sweet potato leaf curl virus (SPLCV), Tobacco leaf curl Japan virus (TbLCJV), Tomato golden mosaic virus (TGMV), Tomato leaf curl Bangalore virus (ToLCBV), Tomato leaf curl Bangladesh virus (ToLCBDV), Tomato leaf curl Karnataka virus (ToLCKV), Tomato leaf curl New Delhi virus (ToLCNDV), Tomato leaf curl Laos virus (ToLCLV), Tomato leaf curl Malaysia virus (ToLCMV), Tomato mottle virus (TMoV), Tomato yellow leaf curl virus (TYLCV), Tomato yellow leaf curl Sardinia virus (TYLCSV) and Watermelon chlorotic stunt virus (WCSV). Species/strain designation follows accepted conventions. Database sequence accession numbers are indicated.
References
Banks G, Bedford ID, Markham PG, 1999. A novel geminivirus of Ipomea
indica (Convolvulaceae) from southern Spain. Plant Disease83, 486.
Lotrakul P, Valverde RA, 1999. Cloning of a DNA A-like component of
sweet potato leaf curl virus: nucleotide sequence and phylogenetic
relationships. Molecular Plant Pathology On-Line
http://www.bspp.org.uk/mppol/1999/0206LOTRAKUL.
This report was formally published in Plant Pathology
+
