In Liguria, incidence of infection has not to positions in the U67449 sequence.
been high but both TICV and T. vaporariorum
This report provides additional informa-
are present and the danger of serious infection is tion about the increasing damage that whitefly-
acute, especially as ornamentals and vegetables – transmitted viruses are causing to protected crops
many of them hosts of TICV (12) – are cultivated worldwide. The cause of the sudden emergence
in proximity.
of crinivirus diseases in Italy is not obvious
The TICV-specific 501 bp fragments ampli- and probably complex. Particular environmen-
fied from three samples (TICV-L from Lazio, tal conditions associated with the presence of
TICV-S from Sardinia and TICV-T260 from Lig- virus reservoirs in particular crops, relaxation of
uria) were purified using a High Pure PCR kit defence measures against whiteflies, and diffi-
(Roche) and sequenced in both directions using culty in recognizing the symptoms, may all have
the same primers designed for amplification. The played a part. Here we describe RT-PCR and
sequences obtained showed more than 99% iden- hybridization diagnostic techniques for TICV
tity to that of TICV strain ‘California’ (Genbank which, together with those described for ToCV
acc. no. U67449), confirming identification. (7), provide useful tools for detection of these
When aligning TICV-T260 (GenBank acc. no. viruses.
AY048855), TICV-L (AY048856) and TICV-S
The whitefly T. vaporariorum, distributed
(AY048857) with the sequence U67449, three throughout the world (2), and TICV, represent
base changes were found. Whereas there was a a severe threat to tomato crops in Europe and
silent base change at position 486, the changes worldwide. As a consequence, searching for
at position 316 and 419 resulted in amino acid sources of resistance or tolerance and breeding
changes of threonine to alanine and alanine to them into cultivated tomato will be the most
valine, respectively. TICV-L contained a further effective way to cope with the problem in the
silent base change at position 75. Numbers refer future.
ACKNOWLEDGMENTS
We thank V. Lisa for providing the TICV-infected sample; colleagues from ERSAT, Sardinia, Italy, and M.
Davino, University of Catania, Italy, for providing samples and information; D. Marian for technical assistance;
and R.G. Milne, M. Conti and P. Caciagli for critical reading of the manuscript.
REFERENCES
1. Accotto, G.P., Vaira, A.M., Vecchiati, M., Finetti-Sialer, M.M., Gallitelli, D. and Davino, M. (2001) First
report of Tomato chlorosis virus in Italy. Plant Dis. 85:1208.
2. Caciagli, P. (2001) Whitefly-borne viruses in Continental Europe. in: Harris, K.F., Duffus, J.E. and Smith,
O.P. [Eds.] Virus-Insect-Plant Interactions. Academic Press Inc., San Diego, CA, USA. pp. 279-292.
3. Dellavalle, G., Caciagli, P., Bosco, D., Lisa, V., d’Aquilio, M., Milne, R.G. et al. (1995) A whitefly-
transmitted clostero-like virus isolated from diseased tomato. Proc. 8th Conf. on Virus Diseases of Vegetables
– Advances in Vegetable Virus Research (Prague, Czech Republic).
4. Duffus, J.E., Caciagli, P., Liu, H.Y., Wisler, G.C. and Li, R. (1996) Occurrence of tomato infectious
chlorosis in Europe. Proc. 4th Annual Progress Review of the 5-Year National Research and Action Plan
for Development of Management and Control Methodology for Silverleaf Whitefly (San Antonio, TX, USA),
p. 30.
5. Duffus, J.E., Liu, H.-Y. and Wisler, G.C. (1996) Tomato infectious chlorosis virus - A new clostero-like virus
transmitted by Trialeurodes vaporariorum. Eur. J. Plant Pathol. 102:219-226.
6. Li, R.H., Wisler, G.C., Liu, H.-Y. and Duffus, J.E. (1998) Comparison of diagnostic techniques for detecting
tomato infectious chlorosis virus. Plant Dis. 82:84-88.
7. Louro, D., Accotto, G.P. and Vaira, A.M. (2000) Occurrence and diagnosis of tomato chlorosis virus in
Portugal. Eur. J. Plant Pathol. 106:589-592.
8. Luisoni, E., Milne, R.G., Caciagli, P., Accotto, G.P., Conti, M., Gallitelli, D. et al. (1989) A geminivirus
associated with a severe leaf curl disease of tomato in Sardinia. 6th Conf. on Recent Advances in Vegetable
Virus Research (Asilomar, CA, USA), pp. 13-14.
Phytoparasitica 30:3, 2002
293