Developmental and postharvest physiological phenotypes of engineered potatoes (Solanum tuberosum L.) grown in the Columbia Basin

The Innate® potato cultivars, Glaciate, Acclimate, and Hibernate are engineered for bruise and cold sweetening resistance, low acrylamide forming potential and increased Late Blight resistance. Phenotyping trials from 2015 to 2017 characterized the in-field performance, postharvest physiology, and process quality of these cultivars in the Columbia Basin of Washington. Plant growth, tuber yields and specific gravities of Acclimate and Hibernate were comparable to their respective parental cultivars, Ranger Russet and Atlantic. Glaciate exhibited lower yield and specific gravity compared with Russet Burbank. All Innate® cultivars had lower reducing sugars at harvest than their conventional counterparts resulting in superior process fry color. Asparagine (Asn) increased many-fold during development of Russet Burbank and Atlantic tubers but remained relatively low in Innate® tubers due to silenced Asn synthetase. Tuber respiration rates during sequential periods of low temperature sweetening (LTS, 4 °C), reconditioning (16 °C), and subsequent cold storage (4 °C) were largely comparable for Acclimate versus Ranger and for Hibernate versus Atlantic. Glaciate tubers, however, maintained significantly higher respiration rates than Russet Burbank tubers. Silenced invertase conferred resistance to reducing sugar buildup at 4 °C, resulting in superior process quality of the Innate® cultivars regardless of storage temperature. However, cold storage (4 °C) induced substantial increases in Suc concentration of Innate® tubers, which was then lowered 43–73 % by reconditioning at 16 °C. Subsequent storage at 4 °C had no further effect on Suc concentrations, demonstrating the efficacy of reconditioning as a management technique to reduce and minimize Suc levels during prolonged cold storage of Innate® tubers. While heat stress exacerbated the cold-induced buildup of Suc in Innate® tubers and reducing sugars in the parental cultivars, the increases in total sugar (Suc + Glc + Fru) concentrations remained equal, indicating similar elevated levels of starch catabolism during LTS of heat-stressed tubers. However, by virtue of silenced invertase, Innate® tubers were highly tolerant of heat stress for retention of process quality.