Polyploidization disrupts drought priming in the desert wild potato species Solanum kurtzianum

Climate change-induced droughts threaten biodiversity and global food security, highlighting the importance of understanding the factors that enhance stress tolerance. Wild potato species are valuable genetic resources for improving stress tolerance in this major crop, but the interaction between polyploidy and stress priming remains poorly understood. In this study, we investigated the effects of ploidy level and drought priming in the desert wild potato Solanum kurtzianum using an euploid series (a diploid genotype K and two derived synthetic autotetraploid lines; A1 and A3). Tubers from well-watered plants (non-primed) or from plants exposed to moderate water deficit (primed) conditions were subsequently exposed to either well-watered or drought treatments. Drought reduced plant height, biomass, tuber number, and weight across all genotypes, while also lowering stomatal conductance and leaf relative water content. Priming effects were genotype-dependent: primed diploid K plants exhibited higher tuber weight and improved drought tolerance indices compared with their non-primed counterparts and with autotetraploid lines, regardless of priming status. In contrast, autotetraploids displayed weaker or absent priming responses, suggesting a reduced capacity for stress memory following genome duplication. Our findings demonstrate that polyploidization may impair drought memory in S. kurtzianum, supporting the hypothesis that diploid wild potatoes maintain superior adaptive capacity to recurrent water deficit. These results highlight the importance of considering ploidy effects when exploiting wild relatives for breeding drought-resilient potatoes and underscore potato as a model for studying the evolutionary and mechanistic links between polyploidy and stress priming.