Biodiversity exploitation: Identification of metabolic QTLs using wild species tomato

URIAS U.; ASIS R.; KAMENETZKY L.; MILSTEIN D.; BERMÚDEZ L.; FERNIE A. R.; VAN SLUYS M.A.; ROSSI M.; CARRARI F.

San Pablo, Brasil

Workshop; Reunión anual de la Red Lat-SOL; 2007

Strategies and advances from a current genomic project will be presented. Starting from a recent work that has identify 889 fruit metabolic loci (QML) in an introgression line population (Solanum lycopersicum x Solanum pennellii) (Schauer et al 2006) and using public availability of highly dense tomato maps, allow us to zoom into selected QML for their dissection at the level of major determinant genes. We have selected 18 genomic regions (BINs) that presented: associated metabolite variations, a clear QML fine localization, and QML correlations with yield associated loci. Three complementary approaches were taken to explore the genetic determinants; i) candidates genes identification on 13 BINs were carried out through an exhaustive selection of markers and already mapped genes, along side an evaluation of allelic differences on their primary structure; ii) a physical map strategy for 2 small, highly dense markers BINs with a lack of sequence information on the markers and mapped genes and iii) a combination of i) and ii) for 3 regions of particular interest. The 5 BINs for physical mapping span 61 selected QML and represent approximately 5 % of the whole S. pennelllii genome. Available overgoes sequences on the SGN database (www.sgn.cornell.edu) were used to screen two S. pennellii genomic libraries (LpenBAC and LpenCOS). Two round of screening were performed by pooled batches of overgoes and re-screening positive clones with individual overgo in order to anchor them to the respective marker. At present, a total of 814 positive clones have been detected and 144 clones were anchored to markers in 2 BINs (1C and 2B). The 16 BINs for candidate genes approach span 106 of the selected QML. From a total of 474 selected markers, 224 putative candidates were obtained. Based on the available sequences from Solanum species, primers for PCR amplification for 134 putative candidates were designed. Genes were amplified and sequenced in order to detect possible species polymorphisms. To date 49 and 43 alleles from S. lycopersicum and S. pennellii respectively were obtained and are under sequence characterization.