Transgenic resistance to cucumber mosaic virus in tomato: blocking of long-distance movement of the virus in lines harboring a defective viral replicase gene

• Published in: Phytopathology Vol. 88; no. 10; pp. 1101 - 1107
• Main Authors: Gal-On, A. (ARO, The Volcani Center, Bet Dagan, Israel.), Wolf, D, Wang, Y.Z, Faure, J.E, Pilowsky, M, Zelcer, A
• Format: Journal Article
• Language: English
• Published: St. Paul, MN American Phytopathological Society 01.10.1998
• Subjects: Agronomy. Soil science and plant productions; AMELIORATION DES PLANTES; Biological and medical sciences; BIOLOGICAL DIFFERENCES; CUCUMBER MOSAIC CUCUMOVIRUS; CUCUMIS SATIVUS; CUCUMOVIRUS DEL MOSAICO DEL PEPINO; CUCUMOVIRUS MOSAIQUE DU CONCOMBRE; DIFERENCIAS BIOLOGICAS; DIFFERENCE BIOLOGIQUE; DISEASE RESISTANCE; DISEASE TRANSMISSION; EXPRESION GENICA; EXPRESSION DES GENES; FITOMEJORAMIENTO; Fundamental and applied biological sciences. Psychology; GENE; GENE EXPRESSION; GENE TRANSFER; GENES; GENETIC TRANSFORMATION; GENETIC VARIATION; Genetics and breeding of economic plants; GENOTIPOS; GENOTYPE; GENOTYPES; PATHOGENICITY; PATOGENICIDAD; Pest resistance; PLANT BREEDING; Plant pathogens; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; POUVOIR PATHOGENE; REPLICACION; REPLICATION; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; STRAIN DIFFERENCES; SUSCEPTIBILITY; TRANSFERENCIA DE GENES; TRANSFERT DE GENE; TRANSFORMACION GENETICA; TRANSFORMATION GENETIQUE; TRANSGENIC PLANTS; TRANSMISION DE ENFERMEDADES; TRANSMISSION DES MALADIES; VARIACION GENETICA; VARIATION GENETIQUE; Varietal selection. Specialized plant breeding, plant breeding aims; VIRAL REPLICATION; Plant pathogen; Virus; Resistance; Vegetable crop; Dicotyledones; Cucumber mosaic virus; Angiospermae; Lycopersicon esculentum; Bromoviridae; Cucumovirus; Spermatophyta; Transgenic plant; Solanaceae
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO.1998.88.10.1101

Tomato breeding lines were transformed with a defective replicase gene from RNA 2 of cucumber mosaic virus (CMV). A total of 63 transformants from five tomato genotypes were evaluated for resistance to CMV strains. The responses of R1 transgenic offspring fit into three categories: fully susceptible lines (44%), fully resistant lines (8%), and an intermediate-type mixture of susceptible and resistant seedlings in variable proportions (48%). Further characterization of the response of two highly resistant lines was performed by mechanical inoculation, aphid transmission, or grafting experiments. No virus was detected in noninoculated leaves from these lines, although a low level of virus accumulated initially in the inoculated leaf. The homozygous R2 plants and further generations that were evaluated (up to R5) showed resistance to the Fny-CMV strain, two Israeli isolates tentatively classified as subgroup IA, and K-CMV (a representative of subgroup IB). These lines were partially resistant to LS-CMV (a representative of subgroup II) when a high-virus-titer inoculum was used. Expression of the viral transgene was verified in these lines; however, the expected translation product was not detectable. In grafting experiments, we demonstrated that CMV virions were blocked in their ability to move from infected rootstocks of nontransformed tomato or tobacco into the transgenic scions. Interestingly, virions could not move through a transgenic intersection into the upper scion. These results provide an additional indication that replicase-mediated resistance affects long-distance movement