Identifying genes for the drought-tolerant potato

A major challenge facing potato producers in the coming decades will be to maintain production as the amount of water available for agriculture decreases. This can be best achieved through a deeper understanding of the mechanisms employed by the plants to adapt to water stress conditions and exploiting existing variation in the crop and its wild relatives.

The EU-funded ELITE (Mapping quantitative trait loci for water use efficiency in potato (Solanum tuberosum)) project aimed to increase the scientific knowledge of drought tolerance and water-use efficiency (WUE) in potatoes. The initiative studied physiological mechanisms behind adaptation, identified quantitative trait loci (QTL) for WUE and validated candidate genes.

Researchers compared positions of gene-based markers linked to QTLs on the potato gene sequence in order to identify the candidate genes underlying these QTLs. A controlled experiment was then conducted using varying degrees of water on the cultivar Desiree to better understand the gene expression profile.

Results demonstrated that potato shows genotypic differences in agronomic, morphological and physiological traits under well-watered and water-stressed conditions. Drought stress was found to increase leaf chlorophyll and chlorophyll fluorescence. Moreover, the cultivars showed that a robust shooting system has the potential to increase tuber yield and should be considered for genetic improvement.

Principal component analysis revealed that genotypes behave differently under optimal and water-stressed conditions. An ability to understand these differences will help in breeding a drought-tolerant potato. In addition, analyses of tolerance and susceptibility indices revealed that drought resistance index, drought susceptibility index and harmonised mean production were good selection criteria for screening.

The data gleaned from ELITE will enable scientists to select cultivars under water stress treatment. Further screening can then be conducted to determine the suitability of these genotypes for sustainable production under stress conditions.