Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 2.22

RISK ASSESSMENT OF TRANSGENIC TOMATO RESISTANT TO CUCUMBER MOSAIC VIRUS (CMV) UNDER FIELD CONDITIONS

GRIECO P. D., LACERTOSA G., MORANO M. G., PETROZZA A, CELLINI F.

Metapontum Agrobios, S. S. Jonica 106 Km 448,2, 75010 Metaponto (MT), Italy

agrobios@agrobios.it

cucumber mosaic virus, PGM, tomato, virus resistance, field

Some valuable agricultural practices, as rotation of crops and removal of weeds and crop’s residues or use of insecticides, may be able to control the viral attack, but only partially. In fact, a fast assay bite on a plant treated with insecticides is enough to infect it, also if the aphid subsequently dies. Therefore, alternative solutions were proposed in the art for combating phytoviruses, in general, and CMV in particular, which are essentially based on the introduction of non-conventional resistance’s, or transgenic resistance.

Since the summer of 2000, genetically modified tomato plants expressing the SGP-CP(-) gene of cucumber mosaic virus have been tested under field conditions (in agreement with the legislation and regulations imposed by the Italian Ministry of Health) to assess the level of resistance, agronomic performance and bio-safety aspects. Two regions, Basilicata and Calabria in Italy were selected for field tests, based on the presence of CMV. Agronomic practices and pest control measures used were recommended by regional "Disciplinari di produzione integrata" in each respective area.

Transgenic tomato plants expressing an antisense gene construct to RNA-3 of a subgroup I strain of cucumber mosaic virus (CMV-1) constituted by the untranslated tRNA - like 3’-terminal region, the gene encoding viral coat protein, a leader sequence of viral RNA and part of the subgenomic promoter (SGP-CP).

Many genes derived from plant RNA viruses expressed in transgenic plants confer variable degrees of resistance against infection by viruses that were the original source of the genes and in some cases, by others virus as well. The mechanisms of pathogen derived plant protection is dependent on the characteristics of host plant, challenging viruses, the transgene construct, and possible exogenous factors modulating the interaction. The antisense approach described here is a promising one of a number of strategies developed to protect crop plants from virus infection, its potential utility is related to the replication interference of the non coding RNA.

CMV resistance was confirmed under field conditions though resistance in the field was effective than what was observed in previous growth chamber and greenhouse experiments, the transgenic tomato line showed resistance against a subgroup I and II strains of CMV supporting a non necrogenic and necrogenic variant of satellites RNA.

Chemical analyses of the compositional content of tomato fruits produced by virus-resistant tomato plants were not statistically significantly different from tomato fruit produced by isogenic conventional tomato cultivar.