May 17, 2004
From: American Phytopathological Society, Plant Disease [edited]

Presence of tomato yellow leaf curl virus infecting squash (Cucurbita pepo) in Cuba
Y Martinez Zubiaur, D Fonseca, M Quinones, I Palenzuela, National Center for Animal and Plant Health, Apdo 10 CP 32700, San Jose de las Lajas, Habana, Cuba. Plant Dis 2004; 88: 572, published online as D-2004-0312-01N,
2004. Accepted for publication 27 Jan 2004.

In a survey conducted in Havana Province during Jan and Feb 2003, symptoms of curling and light yellowing of leaves were found in squash plants (_Cucurbita pepo_). DNA from leaves of 6 symptomatic squash plants was
extracted (1) and hybridized at high stringency with specific probes of the intergenic region of Tomato yellow leaf curl virus (TYLCV, genus _Begomovirus_) isolated in Cuba by using a non-radioactive hybridization kit (AlkPhos Direct Labeling and Detection Systems; Amersham Pharmacia Biotech Inc, Piscataway, NJ).

3 samples were positive in the non-radioactive analyses. The same samples were positive using polymerase chain reaction (PCR) when the DNA was analyzed with degenerate primers PAL1v1978/PAR1c715 for DNA-A (5), specific primers, ORITY1/ORITY2, for the intergenic region (2), and overlapping specific primers for TYLCV (3). Fragments of 1.4, 0.750, and 2.8 kb were cloned using pGem-T Easy (Promega, Madison, WI), and the 6 clones obtained were sequenced using the Terminator Cycle Sequencing Kit in a SEQ 4 × 4 machine (Amersham Pharmacia Biotech Inc.).

Sequences of 3 fragments exhibited 95 to 97 per cent homology with TYLCV (GenBank Accession Nos. AF414089 and AF260331). In addition, we did not obtain a PCR product when DNA was amplified using degenerate primers
PBV1c800/PBC1v2039 for DNA-B (4). These results suggest that TYLCV is present in squash in field plantations, and these plants may serve as a virus reservoir for other crops, such as tomatoes.

References:
(1) SL Dellaporta, et al. Plant Mol Biol Rep 1983; 1(4): 19.
(2) Y Martinez, et al. Rev Prot Veg 2003; 18(3): 168.
(3) MK Nakhla, et al. Plant Dis 1994; 78: 926.
(4) M Rojas, et al. Plant Dis 1993; 77: 340.

[To date, there have been 22 ProMED-Plant reports concerning TYLCV since 1999. The virus causes a devastating disease in the Middle East, Africa, South East Asia, and in the western hemisphere. Disease losses can be catastrophic, leading to complete loss. Disease management includes the use of available resistant cultivars, avoidance of peak times of vector activity, changes in cultural practices such as the control of between-season, alternate hosts, as well as the identification of resistance sources and the production of transgenic plants containing resistant genes from wild species. For simplicity, I have included only the 1st and last reports, but all of them are available from the ProMED-mail website.

Additional references:
<http://www.gladescropcare.com/RAMP_update_july.html>, <www.nda.agric.za/docs/npposa/tomatovirus.pdf>, 
<http://www.iia.msu.edu/absp/tomato.html> - Mod.DH]