Agronomic behavior of some tomato varieties and wild relatives infected by TSWV in field conditions.
Costa, J.1 ; Lacasa, A.2; Catala, M.S .1 ;
Contreras, J.2; Nuez, F.3; Jorda C.4; Dlez, M.J.3; Rosella, S.3
1. Horticulture Dept., C.I.D.A., La Alberca, Murcia.
2. Plat Protection Dept., C.I.D.A., La Alberca, Murcia.
3. Biotechnology (Genetics) Dept. Polytechnical University, 46020 Valencia.
4. Plant Protection (Pathology) Dept. Polytechnical University, 46420 Valencia.
A study was made using plant material, derived from Platense, in order to asses their behavior under
natural conditions of infection in the field. The plant used belonged to the Quilquil and Nuco varieties, which bear a
plum-shaped fruit used industrially, and also the Uco Plata and Pitihue varieties, which bear salad fruits. Other
accessions of interest were PE-4 and CIAPAN-20 belonging to L. pimpinellifolium and PI-126944 and PE-23
belonging to L. peruvianum. The susceptible variety used as a control was Rio Grande, used by industries to
produce concentrated tomato, pastes, marketed by the Peto Seed Company.
To assure high levels of infection in field cultivation, transplanting was carried out on the 23 June in a plot,
near peppers grown for paprika, that had been badly affected by the virus. The experimental design consisted of
two repetitions, and each simple plot had a row of 5 plant, 40 cm between plant and with 1 m between each row. At
the end of each simple plot, five plants belonging to the susceptible Rio Grande variety were planted to act as a
control, in order to confirm the onset of the virus.
The disease was recorded based on symptoms and a later ELISA test, using TSWV-L as antiserum
(LOEWE). The evolution of the vector population (Frankliniella occidentalis) was also followed with leaf and flowers
samples taken at 15 days intervals. It had already been noted that the epidemiological evolution of the disease was
closely related to thrips populations in the plant matter assayed. The onset of the virus in the field was, in general,
found in all the plants belonging to the Rio Grande variety, which confirmed the presence of the disease in the test
plots.
The incidence of the disease related to marketable yield differed greatly depending on the plant variety
(table 1). The marketable yield obtained from the industrially used Argentinean varieties, Quilquil and Nuco,
exceeded 5 Kg/m2, which is satisfactory in agronomic terms. In contrast, the control plants did not produce any
saleable harvest, given that all the fruits were infected by TSWV. Therefore, it has been demonstrated that the two
former varieties can be cultivated in the Mediterranean coastal region despite the virus, whereas the latter, Rio
Grande, a more susceptible variety is not useful.
Our results concord with those obtained by researchers in Brazil and Argentina (Calvar and Sansinanea,
1988; Gallardo, 1992; Boiteux et al., 1993), as far as the native species are concerned, which would suggest that
they posses a degree of field resistance against the different isolates of the virus present on the different
continents. It is therefore, important to point out the behavior demonstrated by CIAPAN-20, which proved sensitive
to artificial inoculations, but did not develop symptoms of the disease when cultivated under natural field conditions.
We believe that the type of tolerance shown by this accession should be studied in greater depth, with a view to its
possible use in breeding programs.
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