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[1] Tomato yellow leaf distortion virus
[2] Tobacco yellow crinkle virus, capsicum

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[1] Tomato yellow leaf distortion virus
Date: February 2009
Source: British Society for Plant Pathology, New Disease Reports (NDR) [edited] <http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=019009>

[Ref: E Fiallo-Olive et al: Tomato yellow leaf distortion virus, a new bipartite begomovirus infecting tomato in Cuba. BSPP New Disease Reports, vol. 19: February-August 2009]

In Cuba, the monopartite _Tomato yellow leaf curl virus_ (TYLCV) is the most wide-spread begomovirus infecting tomato that causes the major losses in all production areas, although 2 bipartite begomoviruses affecting tomatoes have been identified. In January 2007, symptoms of yellow mottle and leaf distortion appeared on tomato plants across eastern Cuba. These symptoms differ from those caused by TYLCV in lacking the typical leaf curling.

DNA from 35 symptomatic leaf samples was tested using PCR. The absence of TYLCV was demonstrated in 4 DNA samples which showed the presence of a bipartite begomovirus. These samples showed strong hybridisation signals with _Pepper golden mosaic virus_ genes under low stringency conditions. The positive samples were sequenced and showed the typical genome organization of bipartite begomoviruses.
The sequence was compared with those from other begomoviruses and showed less than 89 percent nucleotide sequence identity (the species demarcation threshold) to all previously reported begomoviruses. The highest identity (83.9 percent) was with Wissadula golden mosaic St Thomas virus.

The data indicate that the begomovirus infecting tomato is a new species for which we propose the name Tomato yellow leaf distortion virus (ToYLDV). Additional work is now needed to determine the distribution of this new virus in tomato production areas of the country and to quantify the losses it causes.

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[2] Tobacco yellow crinkle virus, capsicum
Date: February 2009
Source: British Society for Plant Pathology, New Disease Reports (NDR) [edited] <http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=019010>


[Ref: E Fiallo-Olive et al: Tobacco yellow crinkle virus, a new bipartite begomovirus infecting tobacco and pepper in Cuba. BSPP New Disease Reports, vol. 19: February-August 2009]

Recently 2 bipartite begomoviruses have been reported infecting tobacco in the country, Tobacco leaf rugose virus (TbLRV) and Tobacco leaf curl Cuba virus (TbLCuCUV). In January 2007, foliar yellowing and crinkling symptoms appeared on tobacco plants in eastern Cuba.

DNA from 7 leaf samples showing symptoms tested by PCR for _Tomato yellow leaf curl virus_ (TYLCV) demonstrated the absence of TYLCV, the most widespread begomovirus in the region. All 7 samples showed amplification for genome components DNA A and B (amplicons of approximately 1.1 and 0.6 kb, respectively) demonstrating the presence of bipartite begomovirus. The same samples showed strong hybridisation signals with _Pepper golden mosaic virus_ genes under low stringency conditions. The positive samples were sequenced and showed 100 percent identity [with each other]. The genome organization was typical of that of the DNA-A components of bipartite begomoviruses originating from the New World. The sequence was compared with those of other begomoviruses and showed less than 88 percent nucleotide sequence identity to all previously reported begomoviruses. The highest levels of identity were with _Cabbage leaf curl virus_ (81.9 percent), TbLCuCUV (74 percent), and with TbLRV
(73.9 percent).

At the same time foliar yellow mottle symptoms were observed on sweet pepper plants (_Capsicum annuum_) in eastern Cuba and the presence of a bipartite begomovirus was demonstrated. The DNA-A component of the virus from one sample was cloned and sequenced. This showed 99.3 percent nucleotide sequence identity to the virus from tobacco. Thus the virus identified in both tobacco and pepper is a new begomovirus species for which the name Tobacco yellow crinkle virus (TbYCV) is proposed.

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[Begomoviruses (family _Geminiviridae_) affect many economically important crops causing symptoms often including leaf yellowing, distortion, stunting, reduced plant vigour, and significant yield losses. They are transmitted by different whitefly species (which are a serious pest in themselves) and many may also be transmitted by mechanical means and grafting, but they are not seed transmitted.
Disease management of begomoviruses may include use of certified virus-free plant material and other means of pathogen exclusion, as well as control of the vector and possible pathogen and/or vector reservoir plants. Begomovirus control is particularly difficult in open field crops due to the widespread presence and wide host range of whiteflies. In some cases, crop cultivars with increased virus resistance are available.

Wissadula golden mosaic St Thomas virus, Tobacco leaf rugose virus and Tobacco leaf curl Cuba virus have at present been registered only as tentative members of the genus by the International Committee on Taxonomy of Viruses (ICTV).

Maps of Cuba:
<http://www.caribnationtv.com/images/maps/cuba.jpg>  and <http://healthmap.org/promed?v=21.6,-79,5>

Pictures
Electron micrograph of _Begomovirus_ particles:
<http://www.ncbi.nlm.nih.gov/ICTVdb/WIntkey/Images/em_gemin_2.jpg>
Whiteflies:
<http://www.honolulurosesociety.org/images/Whiteflies-MC_1.jpg>

Links
Genus _Begomovirus_ taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.029.0.03.htm>
_Begomovirus_ species list:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/fs_gemin.htm#Genus3>
Taxonomy of all other viruses via:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/vn_index.htm>
Information on whiteflies:
<http://entomology.ifas.ufl.edu/fasulo/whiteflies/>  and <http://www.uckac.edu/whitefly/faqs_about_whiteflies.htm>.  - Mod.DHA]

[see also in the archive:
2008
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Mosaic disease, cassava - Congo 20081119.3647 Mosaic viruses, cassava - Uganda, Kenya 20081009.3197 Spearmint disease - India: new begomovirus 20081005.3140 Tomato chlorosis virus - Cuba: 1st report 20080530.1741 Tomato golden mottle virus - Mexico: 1st rep, (SLP) 20080310.0977 Squash leaf curl China virus, pumpkin - Thailand: 1st rep. 20080306.0921 Viruses, potato - UK: (Scotland) 20080130.0383 Brown streak, cassava - East Africa: update 20080107.0084
2007
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Tomato viruses TSWV, TICV - Jordan: 1st reports 20071223.4123 Yellow leaf curl begomoviruses - Netherlands, Taiwan: 1st reports
20071128.3837
Tomato torrado virus - Poland: (Greater Poland), 1st report 20071113.3684 Mungbean yellow mosaic virus, pulses - India (Punjab) 20070905.2921 Viruses, sweet potato - worldwide: synergism 20070624.2042 Diseases, cassava, banana, coffee - Africa: control update 20070617.1970 Mosaic disease, cassava - Tanzania: spread 20070529.1737 Cucurbit virus, CYSDV, melon - USA (AZ): Attempts of control 20070425.1345 Tomato yellow leaf curl virus - USA (California, Texas) 20070413.1228 Cassava brown streak disease, cassava - Uganda (Mukono) 20070405.1147 Yellow leaf curl, tomato - USA (AZ): 1st report 20070226.0694 and older items in the archives]