Three years survey of Tomato yellow leaf curl Sardinia virus reservoir weed hosts in southern Italy.
During the period from August 2004 to June 2006 a serious tomato yellow leaf curl epidemic caused by both Tomato yellow leaf curl Sardinia virus (TYLCSV) and Tomato yellow leaf curl virus (TYLCS) was observed in protected tomato crops in Castrovillari, Calabria Region, in a group of greenhouses where tomato is grown hydroponically. A three years survey for reservoir weed hosts of these viruses was performed during summer period in order to identify where the viruses persist during the host-free period, interesting an area covering a ray of 500 m around the group of greenhouses. About 350 samples were collected from symptomless and symptomatic plants of the following botanic families: Graminaceae, Compositeae, Solanaceae, Portulacaceae, Malvaceae, Chenopodiaceae, Amaranthaceae, Convolvulaceae, Brassicaceae, Labiatae, Plantaginaceae, Asteraceae. Any virus presence was evaluated by DAS ELISA, using a "broad-spectrum" reagent combination detecting different Begomoviruses including TYLCSV and TYLCV. A couple of synthetic oligonucleotides allowing the amplification of the whole coat protein (CP) gene was used for PCR of ELISA positive samples in order to perform the molecular characterisation of the viral isolate responsible of the disease. RFLP analysis performed on the PCR product, 1008 bp long, showed the presence of only TYLCSV in the weeds found infected and belonging to Sonchus asper, Solanum nigrum, Datura stramonium and Cardaria draba species. Similarity analysis performed between the CP of each isolate and the TYLCSV isolate recovered within the greenhouse and responsible of the epidemic in mixed infection with a TYLCV isolate resulted in a value of 100% of identity, thus indicating that there was no variability in TYLCSV population in the surveyed area. S. asper, S. nigrum, D. stramonium and C. draba, as alternative hosts of TYLCSV and nutrient plants of the virus vector, Bemisia tabaci, were found to play an important role in virus ecology and epidemiology in the studied tomato ecosystem. No weed between those investigated has been found to be infected by TYLCV so far. To our knowledge this is the first report of S. asper and C. draba as TYLCSV hosts in natural infection.
Fanigliulo
Angele
A
Dipartimento di Biologia, Difesa e Biotecnologie Agro-Forestali, Università degli Studi della Basilicata, Campus Macchia Romana 1T-3A310 Potenza, Italy.
Pacella
Rosa
R
Comes
Soccorsa
S
Crescenzi
Aniello
A
D000818:Animals; D053839:Begomovirus / Q000302:isolation & purification* / Q000472:pathogenicity; D004197:Disease Reservoirs / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006430:Hemiptera / Q000821:virology*; D018527:Hydroponics; D007558:Italy; D018551:Solanum lycopersicum / Q000821:virology*; D010935:Plant Diseases / Q000821:virology*; D006109:Poaceae / Q000821:virology*; D016133:Polymerase Chain Reaction / Q000379:methods; D013045:Species Specificity