Exploring Heat Stress Response in Genetically and Nutraceutically Diverse Tuscan Potato Landraces Using the Innovative Microcosmo Platform

The study investigated the physiological response to heat exposure of three potato landraces (Biancona del Faggeto, Rossa delle Macchie, and Quarantina delle Macchie), which are primarily grown in the rural area of Mount Amiata (Grosseto, Tuscany) and are distinguished by specific phylogenetic relationships and nutraceutical composition. Nutraceutical and genetic analyses were performed on tubers collected from the field, whereas physiological assessments were conducted on plants grown in Microcosmo simulators. Overall, nutraceutical analyses revealed tissue-specific differences in the distribution of starch and antioxidants, with ‘Biancona del Faggeto’ and ‘Quarantina delle Macchie’ accumulating more starch in the pulp than in the peel. The level of polyphenols and antioxidants differed between the pulp and the peel, but they accumulated most in the peel of ‘Biancona’. Phylogenetic analysis revealed that ‘Rossa’ and ‘Quarantina’ were more closely related than ‘Biancona’. Given that ‘Biancona’ also contained more starch and antioxidants than the others, this suggests a strong relationship between the phylogeny of the potato varieties and their nutritional content. Heat stress reduced net carbon assimilation and stomatal conductance in all landraces, with ‘Quarantina’ showing the greatest reductions, indicating that stomatal closure is the primary limitation of CO2 uptake. However, both the maximum and actual quantum yields of photosystem II remained stable under heat stress, indicating that the primary limitation was not caused by damage to photosynthesis light-dependent reactions. These findings highlight the complex interplay between the genetic background and nutraceutical capacity of potato plants, as well as their physiological adaptability to withstand environmental stressors, and provide valuable insights for breeding healthier and more heat-tolerant potato landraces.