The firmness of fleshy fruit crops has a significant effect on their quality, consumer preference, shelf life and transportability. In a combined quantitative trait locus and genome‐wide association studies study of apple fruit texture, we identified a mutation (C‐G) in the ethylene response factor‐associated amphiphilic repression (EAR) motif in the coding region of the apple ETHYLENE RESPONSE FACTOR4 (ERF4 ) gene. Chromatin immunoprecipitation sequencing showed that ERF4 binds to the promoter of ERF3 , which is involved in regulation of ethylene biosynthesis. The EAR mutation in ERF4 results in reduced repression of ERF3 expression, which is turn promotes ethylene production and loss of fruit firmness. ERF4 acts as a transcriptional repressor whose activity is modulated by a TOPLESS co‐repressor 4 (TPL4)‐binding EAR repression motif. Biolayer interferometry analysis showed that the mutation in the EAR motif causes a reduction in the interaction with TPL4. Suppression of ERF4 or TPL4 promoted fruit ripening and ethylene production. Taken together, our results provide insights into how ERF4 allelic variation underlies an important fruit quality trait.

中文翻译：

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ERF4通过降低乙烯产量，通过TPL4影响果实硬度。

肉质水果作物的坚硬程度对其质量，消费者喜好，保质期和可运输性具有重要影响。在对苹果果实质地的定量性状基因座和全基因组关联研究的联合研究中，我们在苹果ETHYLENE RESPONSE FACTOR4编码区中的乙烯反应因子相关两亲阻抑（EAR）基序中发现了一个突变（C-G）。 （ERF4）基因。染色质免疫沉淀测序表明ERF4结合于启动子虫eRF3，其参与乙烯生物合成的调节。ERF4中的EAR突变导致ERF3的抑制降低表达，从而促进乙烯的生产和水果硬度的损失。ERF4充当转录阻遏物，其活性受TOPLESS协同阻遏物4（TPL4）结合的EAR抑制基序调节。生物层干涉分析表明，EAR基序中的突变导致与TPL4的相互作用降低。ERF4或TPL4的抑制促进了果实的成熟和乙烯的产生。综上所述，我们的结果提供了有关ERF4等位基因变异如何构成重要水果品质性状的基础的见解。