Normal adult survival but reduced Bemisia tabaci oviposition rate on tomato lines carrying an introgression from S. habrochaites

Abstract

Doc number: 142

Abstract

Background: Host plant resistance has been proposed as one of the most promising approaches in whitefly management. Already in 1995 two quantitative trait loci (Tv-1 and Tv-2 ) originating from S. habrochaites CGN1.1561 were identified that reduced the oviposition rate of the greenhouse whitefly (Trialeurodes vaporariorum ). After this first study, several others identified QTLs affecting whitefly biology as well. Generally, the QTLs affecting oviposition were highly correlated with a reduction in whitefly survival and the presence of high densities of glandular trichomes type IV. The aim of our study was to further characterize Tv-1 and Tv-2 , and to determine their role in resistance against Bemisia tabaci.

Results: We selected F₂ plants homozygous for the Tv-1 and Tv-2 QTL regions and did three successive backcrosses without phenotypic selection. Twenty-three F₂ BC₃ plants were phenotyped for whitefly resistance and differences were found in oviposition rate of B. tabaci . The F₂ BC₃ plants with the lowest oviposition rate had an introgression on Chromosome 5 in common. Further F₂ BC_4, F₂ BC₄ S₁ and F₂ BC₄ S₂ families were developed, genotyped and phenotyped for adult survival, oviposition rate and trichome type and density. It was possible to confirm that an introgression on top of Chr. 5 (OR-5 ), between the markers rs-2009 and rs-7551, was responsible for reducing whitefly oviposition rate.

Conclusion: We found a region of 3.06 Mbp at the top of Chr. 5 (OR-5 ) associated with a reduction in the oviposition rate of B. tabaci . This reduction was independent of the presence of the QTLs Tv-1 and Tv-2 as well as of the presence of trichomes type IV. The OR-5 locus will provide new opportunities for resistance breeding against whiteflies, which is especially relevant in greenhouse cultivation.