Wu Chaojie, Cai Danling, Li Jun, Lin Zengxiang, Wei Wei, Shan Wei, Chen Jianye, Lu Wangjin, Su Xinguo, Kuang Jianfei
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables/Engineering Research Center of Southern Horticultural Products Preservation, Ministry of Education, College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Agronomy Dean, Guangdong AIB Polytechnic College, Guangzhou 510507, China.
Hortic Res. 2024 Feb 23;11(4):uhae053. doi: 10.1093/hr/uhae053. eCollection 2024 Apr.
Texture softening is a physiological indicator of fruit ripening, which eventually contributes to fruit quality and the consumer's acceptance. Despite great progress having been made in identification of the genes related to fruit softening, the upstream transcriptional regulatory pathways of these softening-related genes are not fully elucidated. Here, a novel gene, designated as , was identified because of its significant upregulation in banana fruit ripening. DAP-Seq analysis revealed that MabHLH28 bound to the core sequence of 'CAYGTG' presented in promoter regions of fruit softening-associated genes, such as the genes related to cell wall modification (, , , , , , , and ) and starch degradation ( and ), and these bindings were validated by EMSA and DLR assays. Transient overexpression and knockdown of in banana fruit resulted in up- and down-regulation of softening-related genes, thereby hastening and postponing fruit ripening. Furthermore, overexpression of in tomato accelerated the ripening process by elevating the accumulation of softening-associated genes. In addition, MabHLH28 showed interaction withMaWRKY49/111 and itself to form protein complexes, which could combinatorically strengthen the transcription of softening-associated genes. Taken together, our findings suggest that MabHLH28 mediates fruit softening by upregulating the expression of softening-related genes either alone or in combination with MaWRKY49/111.
质地软化是果实成熟的一个生理指标，最终影响果实品质和消费者的接受度。尽管在鉴定与果实软化相关的基因方面取得了很大进展，但这些软化相关基因的上游转录调控途径尚未完全阐明。在这里，一个新的基因，命名为 ，因其在香蕉果实成熟过程中显著上调而被鉴定出来。DAP-Seq分析表明，MabHLH28与果实软化相关基因启动子区域中呈现的“CAYGTG”核心序列结合，这些基因包括与细胞壁修饰相关的基因（ 、 、 、 、 、 、 和 ）以及淀粉降解相关的基因（ 和 ），并且这些结合通过EMSA和DLR分析得到了验证。在香蕉果实中瞬时过表达和敲低 导致软化相关基因的上调和下调，从而加速和延缓果实成熟。此外，在番茄中过表达 可通过提高软化相关基因的积累来加速成熟过程。此外，MabHLH28显示与MaWRKY49/111相互作用并自身形成蛋白质复合物，这可以联合增强软化相关基因的转录。综上所述，我们的研究结果表明，MabHLH28通过单独或与MaWRKY49/111联合上调软化相关基因的表达来介导果实软化。
