The interaction of CpEBF1 with CpMADSs is involved in cell wall degradation during papaya fruit ripening. Issue 1 (1st January 2019)

• Record Type: Journal Article
• Authors: Ding, Xiaochun; Zhu, Xiaoyang; Ye, Lanlan; Xiao, Shuangling; Wu, Zhenxian; Chen, Weixin; Li, Xueping
• Is Part Of: Horticulture research. Volume 6:Issue 1(2019)
• Publication Date: 2019-01-01
• Subjects: Plant signalling -- Transcriptional regulatory elements; Horticulture -- Research -- Periodicals; 635.072
• DOI: 10.1038/s41438-018-0095-1
• Languages: English
• ISSNs: 2052-7276

Abstract

Abstract: Ethylene plays a pivotal role in climacteric fruit ripening; whereas 1-MCP, a non-toxic antagonist of ethylene, prevents ethylene-dependent responses and fruit ripening. In this study, a short-term treatment (1 h) with 400 nL L −1 1-MCP delayed the ripening of harvested papaya. However, long-term application of 1-MCP (400 nL L −1, 16 h) resulted in abnormal fruit ripening, with the fruits exhibiting normal yellowing without softening, significantly higher cellulose and lignin contents, and intact cell walls (CW). Furthermore, we found that long-term treatment with 1-MCP significantly inhibited the expression of CpEBF1, an EIN3-binding F-box-1 gene. A protein interaction analysis using yeast two-hybrid, BiFC and GST pull-down assays showed that CpEBF1 interacts with the CpMADS1/3 and CpEIL1 proteins. The interaction of CpEBF1 with CpMADS1/3 further activated the activities of CW-degradation gene promoters. Subcellular localization showed that these proteins were localized in the nucleus. Additionally, the expression levels of CpMADS1/3, CpEIL1, and several CW-degradation-related genes were significantly downregulated by long-term 1-MCP treatment. Therefore, we propose that the inhibited expression of CpEBF1 and CpMADS1/3 resulted in the repressed activation of CW-degradation-related genes via their interaction, thereby resulting in fruit softening disorders. Papaya: Anti-ripening treatment prevents degradation of cell wall: Long-term treatment with an anti-ripening agent inhibits the expression of regulatory genes that normally break down the cell wall of the papaya fruit. A team from Guangzhou's South China Agricultural University led by Xueping Li and Weixin Chen applied a hormone inhibitor to papayas at the breaker stage of fruit ripening. 1 h of treatment delayed ripening, whereas 16 h of treatment caused the fruit to become rubbery, with significantly higher levels of cellulose and lignin, both structural components of the cell wall. The researchers identified two genes with reduced expression following extended hormone-blocking treatment. Both normally encode proteins that aid in degrading the cell wall to promote fruit ripening. The findings thus offer a molecular explanation for why misuse of anti-ripening agents on papaya fruits can lead to undesirable characteristics.