Testing resistance to TSWV introgressed from Lycopersicon peruvianum by artificial transmission techniques

Abstract

Three lines of Lycopersicon esculentum (RDD, UPV 1 and UPV 32) with resistance to TSWV introgressed from L. peruvianum have been tested. RDD is a carrier of the SW5 gene and the other two lines have been developed at the Universidad Politécnica de Valencia (UPV) from accessions collected in the Andean region. Two methods of artificial inoculation, mechanical and by Frankliniella occidentalis populations, and three highly virulent Spanish isolates of TSWV have been used. Inoculation by populations of thrips proved to be more efficient than mechanical transmission independently of the considered isolate. The three lines were completely resistant when mechanical transmission was used. Also RDD and UPV 1 showed high resistance levels by thrips inoculation method; the isolates had the same effect on these two genotypes. Nevertheless, UPV 32 shows a partial resistance depending on the isolate utilized. The inoculation of virulent isolates by thrips under a high pressure of inoculum caused infection in a few plants of the three genotypes tested. In spite of being the most efficient at present for their unspecificity to isolates (and so the most used by breeders), resistance conferred by SW5 does not guarantee the absence of infection depending on the prevailing crop conditions.