ARS | Publication request: Wild tomato introgressions that confer resistance to begomoviruses in Guatemala

Submitted to: Solanaceae International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2011
Publication Date: February 17, 2011
Citation: Mejia, L., Fulladolsa, A.C., Mendez, L., Melgar, S., Hutton, S., Scott, J.W., Havey, M.J., Maxwell, D.P. 2011. Wild tomato introgressions that confer resistance to begomoviruses in Guatemala ]abstract]. Solanaceae International Congress Proceedings. Available: http://www.sol-symposium2011.com/sci-program.aspx.

Technical Abstract: Begomoviruses, whitefly-transmitted geminiviruses, are one of the major diseases of tomatoes in subtropical and tropical regions. In Guatemala, several bipartite begomoviruses and the monopartite geminivirus, Tomato yellow leaf curl virus, are present. Three experiments were conducted to evaluate the effectiveness of introgressions from wild tomato species against begomoviruses in field trials. First experiment was the evaluation of Ty3-introgression in F3 families. The begomovirus-resistant inbred, Gh13, was selected from a hybrid, FAVI 9, provided by F. Vidavsky and H. Czosnek (Hebrew University of Jerusalem); and this inbred had an introgression in chromosome 6 from 6 to 32 cM. Gh13 was crossed with the susceptible inbred, M82 (ty3/ty3), and homozygous Ty3 and ty3 plants were selfed to create F3 families. A disease severity index (DSI) scale from 0 = resistant, no symptoms to 6 = susceptible, stunted, no fruit was used. The mean DSI (2.0) for the Ty3 families was less than for the mean DSI (4.5) for the ty3 families. Second experiment involved assessment of DSI’s for RILs (Gh13 x HUJ, a very susceptible inbred). All forty-six RILs with ty3/ty3 genotype had DSI’s =4.1 and the 41 Ty3/Ty3 RILs were divided into three groups, 9 RILs resistant, 7 RILs moderately resistant and 25 RILs susceptible. One conclusion is that other genes besides those associated with the Ty3 marker are important in resistance. Third experiment involved evaluation of the effectiveness of five begomovirus-resistance introgressions (Ty1, Ty2, Ty3, Ty3a, and Ty4). In general, the Ty3a/Ty3a genotypes were the most resistant and Ty1 and Ty2 were least effective. The heterozygous genotype, Ty3a/ty3, Ty2/ty2, was also highly resistant. Results support a strategy of using different resistance introgressions in hybrid development and that multiple genes are involved in resistance.