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Article|14 Feb 2023|OPEN
Generating colorful carrot germplasm through metabolic engineering of betalains pigments
Yuan-Jie Deng1 ,† , Ao-Qi Duan1 ,† , Hui Liu1 , Ya-Hui Wang1 , Rong-Rong Zhang1 , Zhi-Sheng Xu1 and Ai-Sheng Xiong,1 ,
1National Key Laboratory of Crop Genetics and Germplasm Enhancement and Utilization, Ministry of Agriculture and Rural Affairs Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
*Corresponding author. E-mail:
Both authors contributed equally to the study.

Horticulture Research 10,
Article number: uhad024 (2023)
Views: 254

Received: 29 Oct 2022
Accepted: 05 Feb 2023
Published online: 14 Feb 2023


Betalains are tyrosine-derived plant pigments exclusively found in the Caryophyllales order and some higher fungi and generally classified into two groups: red-violet betacyanins and yellow-orange betaxanthins. Betalains attract great scientific and economic interest because of their relatively simple biosynthesis pathway, attractive colors and health-promoting properties. Co-expressing two core genes BvCYP76AD1 and BvDODA1 with or without a glycosyltransferase gene MjcDOPA5GT allowed the engineering of carrot (an important taproot vegetable) to produce a palette of unique colors. The highest total betalains content, 943.2 μg·g−1 DW, was obtained in carrot taproot transformed with p35S:RUBY which produces all of the necessary enzymes for betalains synthesis. Root-specific production of betalains slightly relieved tyrosine consumption revealing the possible bottleneck in betalains production. Furthermore, a unique volcano-like phenotype in carrot taproot cross-section was created by vascular cambium-specific production of betalains. The betalains-fortified carrot in this study is thus anticipated to be used as functional vegetable and colorful carrot germplasm in breeding to promote health.