title: Heat stress affects carbohydrate metabolism during cold-induced sweetening of potato (Solanum tuberosum L.).
abstract: Tolerance to heat stress for retention of low-temperature sweetening-resistant phenotype in potato is conferred by insensitivity of acid invertase activity to cold induction. Heat stress exacerbated cold sweetening (buildup of reducing sugars) of the LTS (low-temperature sweetening)-susceptible potato (Solanum tuberosum L.) cultivars, Ranger Russet and Russet Burbank, and completely abolished the resistance to cold sweetening in the LTS-resistant cultivars/clones, Sage Russet, GemStar Russet, POR06V12-3 and A02138-2. Payette Russet and EGA09702-2, however, demonstrated considerable tolerance to heat stress for retention of their LTS-resistant phenotype. Heat-primed Payette Russet and EGA09702-2 tubers accumulated fourfold more sucrose when subsequently stored at 4 °C, while reducing sugar concentrations also increased marginally but remained low relative to the non-heat-tolerant LTS-resistant clones, resulting in light-colored fries. By contrast, sucrose concentrations in heat-primed tubers of the non-heat-tolerant clones remained unchanged during LTS, but reducing sugars increased fivefold, resulting in darkening of processed fries. Acid invertase activity increased in the LTS-susceptible and non-heat-tolerant LTS-resistant cultivars/clones during cold storage. However, Payette Russet tubers maintained very low invertase activity regardless of heat stress and cold storage treatments, as was the case for Innate®Russet Burbank (W8) tubers, where silenced invertase conferred robust tolerance to heat stress for retention of LTS-resistant phenotype. Importantly, heat-stressed tubers of Payette Russet, EGA09702-2 and Innate®Russet Burbank (W8) demonstrated similar low reducing sugar and high sucrose-accumulating phenotypes when stored at 4 °C. Tolerance to heat stress for retention of LTS-resistant phenotype in Payette Russet and likely its maternal parent, EGA09702-2, is, therefore, conferred by the ability to maintain low invertase activity during cold storage of heat-stressed tubers.
authors.affiliation: Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture, Washington State University, P.O. Box 646414, Pullman, WA, 99164-6414, USA.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Herman
authors.affiliation: Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture, Washington State University, P.O. Box 646414, Pullman, WA, 99164-6414, USA.
authors.forename: Lisa O
authors.initials: LO
authors.lastname: Knowles
authors.affiliation: Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture, Washington State University, P.O. Box 646414, Pullman, WA, 99164-6414, USA. rknowles@wsu.edu.
authors.forename: N Richard
authors.initials: NR
authors.lastname: Knowles
mesh_terms: D050260:Carbohydrate Metabolism / Q000187:drug effects; D003080:Cold Temperature; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006358:Hot Temperature; D009929:Organ Size / Q000187:drug effects; D057445:Plant Dormancy / Q000187:drug effects; D035281:Plant Tubers / Q000033:anatomy & histology / Q000187:drug effects; D012621:Seasons; D012987:Soil; D011198:Solanum tuberosum / Q000187:drug effects / Q000502:physiology*; D024941:Starch Phosphorylase / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects; D013649:Taste; D043324:beta-Fructofuranosidase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D012987:Soil; D024941:Starch Phosphorylase; D043324:beta-Fructofuranosidase
keywords: Carbohydrate metabolism; Heat stress; Invertase; Low-temperature sweetening; Reducing sugars; Solanum tuberosum L