Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Identification of Bemisia argentifolii Resistant Loci from Solanum habrochaites Accession LA1777
Gulf Coast Research and Education Center, IFAS, University of Florida, Wimauma, FL, USA
Tomato, Solanum lycopersicon L. (formerly Lycopersicon esculentum Mill.) is a widely distributed and economically important crop throughout the world. Insect pests may limit successful crop production. The silverleaf whitefly (SLWF) Bemisia argentifolii Bellows & Perring [also known as biotype B of the sweetpotato whitefly, B. tabaci (Genn.)] is a particularly destructive pest of tomato in many tropical and subtropical regions. Damage is caused directly by its feeding habit and indirectly by the transmission of more than 50 different begomoviruses. Often SLWF is difficult to control solely with insecticides because of its ability to develop resistance to insecticides, thus causing serious problems for crop producers. Resistant cultivars would be an economical and environmentally sound way of managing B. argentifolii in tomato production. The wild accession LA1777 of S. habrochaites (formerly known as Lycopersicon hirsutum) was reported to be highly resistant to whiteflies. The objective of this study was to identify the gene(s) responsible for resistance to SLWF. In our earlier work no resistance was detected in any recombinant inbred lines (RIL) derived from tomato crossed with LA1777. An interspecific F2 population that was developed in our laboratory was assayed for resistance based on whitefly oviposition in no choice evaluations and on type IV trichome counts. From the F2 population 11 resistant and 10 susceptible plants were selected and were used to locate resistance genes by testing them with molecular markers. Over 400 molecular markers that span the tomato genome at about 10cM intervals have been tested. So far, markers in 5 regions on 4 different chromosomes appear to be associated with resistance, while markers in 4 other regions are less clearly associated with resistance. Crosses have been made between RILs to combine the putative resistance regions. Plants with combined target regions will be assayed for resistance to verify their role in SLWF resistance.