Drought Tolerance in Potato (Solanum tuberosum L.): Marker Development for Potential Candidate Genes

Climate changes and the predicted increasing world population will lead to a challenge for the future world food supply. Therefore, it is essential to develop drought-tolerant varieties in crops like potato, the fourth most important food crop worldwide, providing adequate yields. Marker-assisted selection can be a helpful tool in breeding for this complex trait. A lot of putative candidate genes have been published for drought tolerance involving enzymes of biosynthesis and signaling pathways of plant hormones like abscisic acid or ethylene, osmolytes, detoxification enzymes and transcription factors. In our study, 151 SSR (Simple Sequence Repeat) markers have been derived from 99 candidate genes, gathered from the literature or transcript marker candidates of the project TROST. Gene sequences were extracted from the databases Spud DB, Phytozome, NCBI and Ensembl Plants. Newly derived microsatellite markers were tested in an association panel of 34 starch potato cultivars ranked according to their drought tolerance within TROST. More than half of the tested SSR primer combinations revealed polymorphic banding patterns. Interestingly, five of the SSR markers showed a significant association (p < 0.05) with drought tolerance. In order to map the newly developed microsatellite markers in TetraploidMap, these SSR markers have been analyzed in a segregating F₁ population (> 250 offspring) obtained by a cross of a drought-tolerant and a drought-sensitive cultivar in VALDIS TROST. Furthermore, 22 AFLP (Amplified Fragment Length Polymorphism) primer combinations have been analyzed to saturate the genetic maps. Altogether 290 polymorphic AFLP banding patterns with informative segregation ratios were obtained.