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Peng Z, Song L, Chen M, Liu Z, Yuan Z, Wen H, Zhang H, Huang Y, Peng Z, Yang H, Li G, Zhang H, Hu Z, Li W, Wang X, Larkin RM, Deng X, Xu Q, Chen J, Xu J. Neofunctionalization of an OMT cluster dominates polymethoxyflavone biosynthesis associated with the domestication of citrus. Proc Natl Acad Sci U S A 2024; 121:e2321615121. [PMID: 38530892 PMCID: PMC10998556 DOI: 10.1073/pnas.2321615121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 02/22/2024] [Indexed: 03/28/2024] Open
Abstract
Polymethoxyflavones (PMFs) are a class of abundant specialized metabolites with remarkable anticancer properties in citrus. Multiple methoxy groups in PMFs are derived from methylation modification catalyzed by a series of hydroxylases and O-methyltransferases (OMTs). However, the specific OMTs that catalyze the systematic O-methylation of hydroxyflavones remain largely unknown. Here, we report that PMFs are highly accumulated in wild mandarins and mandarin-derived accessions, while undetectable in early-diverging citrus species and related species. Our results demonstrated that three homologous genes, CreOMT3, CreOMT4, and CreOMT5, are crucial for PMF biosynthesis in citrus, and their encoded methyltransferases exhibit multisite O-methylation activities for hydroxyflavones, producing seven PMFs in vitro and in vivo. Comparative genomic and syntenic analyses indicated that the tandem CreOMT3, CreOMT4, and CreOMT5 may be duplicated from CreOMT6 and contributes to the genetic basis of PMF biosynthesis in the mandarin group through neofunctionalization. We also demonstrated that N17 in CreOMT4 is an essential amino acid residue for C3-, C5-, C6-, and C3'-O-methylation activity and provided a rationale for the functional deficiency of OMT6 to produce PMFs in early-diverging citrus and some domesticated citrus species. A 1,041-bp deletion in the CreOMT4 promoter, which is found in most modern cultivated mandarins, has reduced the PMF content relative to that in wild and early-admixture mandarins. This study provides a framework for reconstructing PMF biosynthetic pathways, which may facilitate the breeding of citrus fruits with enhanced health benefits.
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Affiliation(s)
- Zhaoxin Peng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
| | - Lizhi Song
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Minghua Chen
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Zeyang Liu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Ziyu Yuan
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Huan Wen
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Haipeng Zhang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- College of Horticulture, Henan Agricultural University, Zhengzhou450046, People’s Republic of China
| | - Yue Huang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Zhaowen Peng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Hongbin Yang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Gu Li
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Huixian Zhang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Zhehui Hu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Wenyun Li
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Guizhou Fruit Institute, Guizhou Academy of Agricultural Sciences, Guiyang550006, People’s Republic of China
| | - Xia Wang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
| | - Robert M. Larkin
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
| | - Xiuxin Deng
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
| | - Qiang Xu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
| | - Jiajing Chen
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
| | - Juan Xu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan430070, People’s Republic of China
- Hubei Hongshan Laboratory, Wuhan430070, People’s Republic of China
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