Genetic dissection of drought tolerance in potato

Drought is the most important cause of crop and yield loss around the world. Breeding for drought tolerance is not straightforward, as drought is a complex trait. A better understanding of the expression of drought traits, the genes underlying the traits and the way these genes interact will significantly increase the success of breeding for drought tolerance. Potato is an important food crop, yet it is relatively susceptible to drought. As a first step towards identifying the genetic basis for drought tolerance in potato, we make use of diploid potato populations that have been genetically well characterized (CxE, SHxRH). The CxE population was extensively evaluated for drought tolerance in vitro and for two successive years (2008, 2009) under greenhouse conditions and the data were used for QTL mapping. For optimal QTL mapping, we expanded the CxE and SHxRH genetic maps with 499 SNP markers (two arrays 384 and 768SNP arrays respectively, enriched for putative stress tolerance candidate genes). The SNPs were discovered in public EST databases using QualitySNP software and detected with the Illumina GoldenGate assay. About 300 SNPs served as bridge markers between the CxE and SHxRH maps. This will enable us to make use of the extensive genetic and sequence information of the SHxRH population and the RH genome sequence. With the availability of the potato genome sequence of the doubled monoploid DM1-3 516R44 (DM) (www.potatogenome.net), it was possible to further examine the SNP marker loci for paralogs and intron spanning sequences. In total 732 SNP marker loci were found to be unique in the potato genome sequence. Many of these SNP markers not only served as landmarks on the genetic map but may also as putative genes underlying quantitative traits. In addition the validated SNP markers are now utilized as anchors in the potato physical map. We investigated the possibility of screening potato for relevant drought traits in in vitro cultures and evaluated the CxE pop