Polyploidization disrupts drought response and epigenetic patterns in the desert wild potato species Solanum...

Polyploidy, the possession of more than two sets of chromosomes in a cell, is often linked to enhanced adaptability and stress resilience in plants, though it may introduce genomic instability and fitness costs. Here, we examined the interplay between ploidy level and epigenetic responses to drought stress in Solanum kurtzianum, a drought-tolerant wild relative of potato. We subjected diploid and newly oryzalin-induced autotetraploid lines to three different watering regimes and assessed their morphological, physiological, biochemical, and epigenetic responses. Diploids consistently outperformed autotetraploids in drought tolerance and tuber yield under moderate water stress, exhibiting lower stomatal conductance, yet maintaining comparable photochemical efficiency. Epigenetic analyses revealed significant interplay between the ploidy level and drought conditions on methylation patterns, with autotetraploids displaying higher methylation variability and greater genomic instability under severe drought. These findings are consistent with the predominance of diploid wild potatoes in arid regions and suggest that genomic instability caused by polyploidy may compromise drought resilience. The study emphasizes the adaptive potential of diploid wild potatoes in arid environments and the role of epigenetic mechanisms in stress responses. Our results have implications for potato breeding strategies, highlighting the potential of diploids for developing drought-resilient cultivars to cope with climate change challenges.