Development and regulatory approval of Kal91.3: combining advanced conventional breeding with genetic engineering to create a cold sweetening‑resistant chip‑processing potato

Abstract

Abstract

Globally, potato (Solanum tuberosum) is an important food crop. Due to an expanding potato‑chip processing market, it is increasingly essential that high-quality raw tubers are maintained and available year-round. Cold storage at temperatures below 10°C greatly increases the duration of potato tuber storage, however, potatoes are susceptible to cold-induced sweetening (CIS). At these temperatures, potato starch stored in the tuber converts to reducing sugars, leading to a dark, bitter-tasting potato chip. Kalkaska is a potato variety with high yield and a highly desirable scab resistance; however, it is unreliable in managing reducing sugars in commercial storage. In this study, we report a comprehensive characterization and analysis of a genetically engineered potato line Kal91.3, utilizing VInv RNAi suppression to correct the reducing sugar management in Kalkaska. A full molecular characterization analysis was completed on Kal91.3, which demonstrated that there are two independent and stable T-DNA insertions. RNA analysis reported suppression of the VInv transcripts, which was further shown during a prolonged tuber storage period. Kalkaska and Kal91.3 tubers were stored at 4°C for up to 8 months. Kal91.3 produced chips light in color, and the Kalkaska control produced dark chips typical of the CIS darkening response. Kal91.3 is the first genetically engineered field‑crop product developed by a non-industry organization and to have received regulatory clearance in the United States. Kal91.3 is expected to provide significant benefits to growers, processors, and consumers by producing high-quality potato chips from long-term, lower-temperature storage, improving supply‑chain stability, and waste reduction.