The Root to Combined Stress Tolerance in Potato

Potato (Solanum tuberosum L.) production currently requires large amounts of phosphorus (P) fertilizer and water. In the interests of sustainable crop production, it is important to reduce these resource inputs and make the system as efficient as possible in the face of climate change. This can be achieved by improving management practices and developing genotypes with better root systems and greater physiological water and phosphorus use efficiencies.

Populations of potato were grown in the field in multiple years both with and without the application of P fertilizer. Phosphorus concentrations in diagnostic leaves ([P]_leaf) were determined at canopy closure and yield and concentrations of mineral elements in tubers were determined at commercial maturity. Quantitative trait loci (QTL) for these traits were determined. Eight genotypes with contrasting agronomic PUE were identified and subsequently assessed for response to P-deficiency. In addition genotypic variation in rooting traits was established in both the glasshouse and the field and was used to predict performance under drought conditions in the field.

Consistent QTL affecting yield and PUE were identified. There were strong positive relationships between root mass at establishment, canopy closure and early tuber biomass accumulation in the field. It was also demonstrated that genotypes with larger root systems had improved drought tolerance. Studies in the glasshouse confirmed that root system parameters correlated well with P uptake and shoot growth, drought tolerance and yield in the field. When grown hydroponically, 73 genes differed in their expression between roots of P-replete and P-starved plants of all genotypes. These genes represent a common transcriptional response to P-starvation and provide candidates for improving stress tolerance. These findings are currently being validated and will increase our understanding of how rooting traits in potato can improve the crop’s ability to cope with abiotic stress in future agro-environments.