Browse Articles

Article|10 Feb 2023|OPEN
CRISPR/Cas9-mediated SNAC9 mutants reveal the positive regulation of tomato ripening by SNAC9 and the mechanism of carotenoid metabolism regulation
Yuan Feng1 , Xiaohong Kou1 , , Shuai Yuan1 , Caie Wu2 , Xiaoyang Zhao1 , Zhaohui Xue1 , Qingxiu Li3 , Zhengyu Huang1 and Yijie Sun,1
1School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
2College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing 210037, China
3College of Food Science and Biological Engineering, Tianjin Agricultural University, Tianjin 300384, China
*Corresponding author. E-mail:

Horticulture Research 10,
Article number: uhad019 (2023)
Views: 218

Received: 21 Nov 2022
Accepted: 03 Feb 2023
Published online: 10 Feb 2023


NAC transcriptional regulators are crucial for tomato ripening. Virus-induced gene silencing (VIGS) of SNAC9 (SlNAC19, Gene ID: 101248665) affects tomato ripening, and SNAC9 is involved in ethylene and abscisic acid (ABA) metabolic pathways. However, the function of SNAC9 in pigment metabolism in tomatoes remains unclear. This work seeks to discover the mechanism of SNAC9 involvement in pigment metabolism during tomato ripening by establishing a SNAC9 knockout model using CRISPR/Cas9 technology. The results indicated that fruit ripening was delayed in knockout (KO) mutants, and SNAC9 mutation significantly affected carotenoid metabolism. The chlorophyll (Chl) degradation rate, total carotenoid content, and lycopene content decreased significantly in the mutants. The transformation rate of chloroplasts to chromoplasts in mutants was slower, which was related to the carotenoid content. Furthermore, SNAC9 changed the expression of critical genes (PSY1PDSCRTISOZ-ISOSGR1DXS2LCYELCYB, and CrtR-b2) involved in pigment metabolism in tomato ripening. SNAC9 knockout also altered the expression levels of critical genes involved in the biosynthesis of ethylene and ABA. Accordingly, SNAC9 regulated carotenoid metabolism by directly regulating PSY1DXS2SGR1, and CrtR-b2. This research provides a foundation for developing the tomato ripening network and precise tomato ripening regulation.