J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (7): 1448-1461.DOI: 10.1111/jipb.13278

• Plant Reproduction Biology • Previous Articles    

Natural variation in the NAC transcription factor NONRIPENING contributes to melon fruit ripening

Jinfang Wang1†, Shouwei Tian1†, Yongtao Yu1†, Yi Ren1, Shaogui Guo1, Jie Zhang1, Maoying Li1, Haiying Zhang1, Guoyi Gong1, Min Wang2 and Yong Xu1*   

  1. 1 National Watermelon and Melon Improvement Center, Beijing Academy of Agricultural and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Beijing Key Laboratory of Vegetable Germplasm Improvement, Beijing 100097, China
    2 Sanya Institute, Hainan Academy of Agricultural Sciences, Haikou 572025, China

    These authors contributed equally to this article.
    * Correspondence: Yong Xu (xuyong@nercv.org)
  • Received:2022-04-22 Accepted:2022-05-12 Online:2022-05-15 Published:2022-07-01


The NAC transcription factor NONRIPENING (NOR) is a master regulator of climacteric fruit ripening. Melon (Cucumis melo L.) has climacteric and non-climacteric fruit ripening varieties and is an ideal model to study fruit ripening. Two natural CmNAC-NOR variants, the climacteric haplotype CmNAC-NORS,N and the non-climacteric haplotype CmNAC-NORA,S, have effects on fruit ripening; however, their regulatory mechanisms have not been elucidated. Here, we report that a natural mutation in the transcriptional activation domain of CmNAC-NORS,N contributes to climacteric melon fruit ripening. CmNAC-NOR knockout in the climacteric-type melon cultivar “BYJH” completely inhibited fruit ripening, while ripening was delayed by 5–8 d in heterozygous cmnac-nor mutant fruits. CmNAC-NOR directly activated carotenoid, ethylene, and abscisic acid biosynthetic genes to promote fruit coloration and ripening. Furthermore, CmNAC-NOR mediated the transcription of the “CmNAC-NOR-CmNAC73-CmCWINV2” module to enhance flesh sweetness. The transcriptional activation activity of the climacteric haplotype CmNAC-NORS,N on these target genes was significantly higher than that of the non-climacteric haplotype CmNAC-NORA,S. Moreover, CmNAC-NORS,N complementation fully rescued the non-ripening phenotype of the tomato (Solanum lycopersicum) cr-nor mutant, while CmNAC-NORA,S did not. Our results provide insight into the molecular mechanism of climacteric and non-climacteric fruit ripening in melon.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q