Screening Two Lycopersicon peruvianum Collections for Resistance to Tomato spotted wilt virus.

The United States Department of Agriculture (USDA) Research Service and the Tomato Genetics Resource Center (TGRC) Lycopersicon peruvianum germplasm collections (16,335 plants from 285 accessions) were screened with the Tomato spotted wilt virus (TSWV) isolates TSWV6 from Hawaii, and An-1 from Western Australia. Using TSWV6 to screen for resistance, 10,634 L. peruvianum plants from 280 accessions were screened for resistance, resulting in 168 (60%) accessions with 1,437 (14%) plants indicating resistance, with all 1,404 89S (Sw-5+/Sw-5+) and 1,456 89R (Sw-5/Sw-5) controls infected. When using An-1 for screening, 864 (15%) of 5,701 L. peruvianum plants were uninfected from 106 of the 181 accessions tested, and 472 (95%) of the 495 89S and 421 (73%) of the 574 89R controls were infected. Of the 172 accessions tested with both isolates, 54 were resistant to one isolate but not the other. Additionally, more accessions from the USDA than from the TGRC collection indicated resistance. TSWV-resistant accessions were somewhat equally distributed throughout the L. peruvianum geographic range, with an observation that northern Chile and southern Peru seemed to have an unusually high portion of accession indicating resistance. The value of Sw-5 is discussed in relationship to potential additional sources of TSWV resistance.