Editing sterol side chain reductase 2 gene (StSSR2) via CRISPR/Cas9 reduces the total steroidal glycoalkaloids in potato

Abstract

Steroidal glycoalkaloids (SGAs) existing in most potato tissues are toxic to humans when the fresh weight is over 200 mg kg⁻¹, and high SGAs content would also damage the quality of potato tubers. Sterol side chain reductase 2 (StSSR2) is a key enzyme in the biosynthetic of SGAs in potatoes. To reduce the concentration of SGAs in tetraploid cultivated potato (Solanum tuberosum L.), the gene StSSR2 was edited by the CRISPR/Cas9 system. A total number of 64 mutant lines were generated, and the mutation efficiency was 46%. The percentage of insertion was 6.25%, and the percentage of deletion was 93.75%. Compared to the wild-type (WT), the content of SGAs reduced significantly in the mutated potatoes. The lowest SGAs concentration was 54% of the WT level, which was recorded in the peels of line #360. In the tuber fleshes, the lowest SGAs were 66% of WT level, which was found in line #378. In the leaves, the lowest SGAs concentration was 44% of the WT level as found in lines #204 and #378. In a word, our results showed that the StSSR2 gene of tetraploid cultivated potato could be successfully edited by the CRISPR/Cas9 system to reduce toxic SGAs.

KEYWORDS:

• CRISPR/Cas9
• genome editing
• multiplex gRNAs
• SSR2
• the tetraploid cultivated potato

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available in the figshare repository (https://figshare.com/) at https://figshare.com/s/790ef87161f5d84bf-cad.

Additional information

Funding

This research was funded by the Modern Agricultural Industry Technology System [Grant Number CARS-9], The R&D and Demonstration of Key Technologies for High-Quality Development of Specialized Potato Industry [ Grant Number 2019-NK-A1] and the Natural Science Foundation of Qinghai Province [Grant Number 2017-ZJ-960Q]. Ministry of Agriculture and Rural Affairs of the People’s Republic of China; Science and Technology Department of Qinghai Province.