EVALUATION OF LYCOPERSICON GERM PLASM FOR TOMATO SPOTTED WILT TOSPOVIRUS RESISTANCE BY MECHANICAL AND THRIPS TRANSMISSION

Selected tomato germ plasm representing eight Lycopersicon species and five cultivars of L. esculentum was evaluated for resistance to a Haw aiian isolate of tomato spotted wilt tospovirus (formerly designated T SWV-L). A comparison of mechanical and thrips inoculation of TSWV acro ss these accessions demonstrated that the two inoculation methods prov ide different evaluations of tomato germ plasm. Mechanical inoculation was useful in identifying direct TSWV resistance, such as virus repli cation and translocation. In contrast, thrips inoculation was most use ful in identifying insect-mediated components of TSWV resistance, such as those associated with changes in feeding behavior. Although both i noculation methods resulted in systemic TSWV infection in all accessio ns except Lycopersicon peruvianum, the percentage of infection varied significantly among germ plasm screened within and between inoculation methods. While L. parviflorum, a wild species, was the most susceptib le accession, L. pennellii, L. chilense, and L. peruvianum were least susceptible to TSWV with both mechanical and thrips inoculations. Thri ps inoculation resulted in significantly fewer infected plants compare d to mechanical inoculation on L. esculenturn cultivars Manzana, Brazi l, and Anahu, and on L. hirsutum f. glabratum, indicating resistance t o thrips transmission of TSWV. The differences observed between mechan ical and thrips inoculation suggest that one should consider results o btained by both methods when evaluating accessions for resistance to T SWV.