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Article|05 Oct 2021|OPEN
An apple (Malus domestica) AP2/ERF transcription factor modulates carotenoid accumulation
Qingyuan Dang1, Haiyun Sha1, Jiyun Nie1, Yongzhang Wang1, Yongbing Yuan1, & Dongjie Jia1,
1Qingdao Key Lab of Modern Agriculture Quality and Safety Engineering, College of Horticulture, Qingdao Agricultural University, Qingdao 266109, China

Horticulture Research 8,
Article number: 223 (2021)
doi: 10.1038/hortres.2021.223
Views: 98

Received: 20 Apr 2021
Revised: 15 Aug 2021
Accepted: 25 Aug 2021
Published online: 05 Oct 2021

Abstract

Color is an important trait for horticultural crops. Carotenoids are one of the main pigments for coloration and have important implications for photosynthesis in plants and benefits for human health. Here, we identified an APETALA2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) transcription factor named MdAP2-34 in apple (Malus domestica Borkh.). MdAP2-34 expression exhibited a close correlation with carotenoid content in ‘Benin Shogun’ and ‘Yanfu 3’ fruit flesh. MdAP2-34 promotes carotenoid accumulation in MdAP2-34-OVX transgenic apple calli and fruits by participating in the carotenoid biosynthesis pathway. The major carotenoid contents of phytoene and β-carotene were much higher in overexpressing MdAP2-34 transgenic calli and fruit skin, yet the predominant compound of lutein showed no obvious difference, indicating that MdAP2-34 regulates phytoene and β-carotene accumulation but not lutein. MdPSY2-1 (phytoene synthase 2) is a major gene in the carotenoid biosynthesis pathway in apple fruit, and the MdPSY2-1 gene is directly bound and transcriptionally activated by MdAP2-34. In addition, overexpressing MdPSY2-1 in apple calli mainly increases phytoene and total carotenoid contents. Our findings will advance and extend our understanding of the complex molecular mechanisms of carotenoid biosynthesis in apple, and this research is valuable for accelerating the apple breeding process.