Natural variation in the NAC transcription factor NONRIPENING contributes to melon fruit ripening. Issue 7 (6th June 2022)

• Record Type: Journal Article
• Authors: Wang, Jinfang; Tian, Shouwei; Yu, Yongtao; Ren, Yi; Guo, Shaogui; Zhang, Jie; Li, Maoying; Zhang, Haiying; Gong, Guoyi; Wang, Min; Xu, Yong
• Is Part Of: Journal of integrative plant biology. Volume 64:Issue 7(2022)
• Page Start: 1448
• Page End: 1461
• Publication Date: 2022-06-06
• Subjects: climacteric fruit -- fruit ripening -- melon -- NAC transcription factor; Plants -- Periodicals; Plants -- China -- Periodicals; Electronic journals; 580.5
• DOI: 10.1111/jipb.13278
• Languages: English
• ISSNs: 1672-9072

Abstract

ABSTRACT: 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‐NOR S, N and the non‐climacteric haplotype CmNAC‐NOR A, 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‐NOR S, 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‐NOR S, N on these target genes was significantly higher than that of the non‐climacteric haplotype CmNAC‐NOR A, S . Moreover, CmNAC‐NOR S, N complementation fully rescued the non‐ripening phenotype of the tomato ( Solanum lycopersicum ) cr‐nor mutant, while CmNAC‐NOR A, S did not. Our results provide insight into the molecular mechanism of climacteric and non‐climacteric fruit ripening in melon. Abstract : CmNAC‐NOR knockout in a climacteric‐type melon cultivar completely inhibited fruit ripening, while ripening was delayed by 5–8 days in heterozygous cmnac‐nor mutant fruits. Natural mutation of CmNAC‐NOR enhanced transcriptional activation of its target genes. These findings may contribute to breeding programs aimed at creating long shelf‐life melons.