BACKGROUND In soft fruits, the differential expression of many genes during development and ripening is responsible for changing their organoleptic properties. In strawberry fruit, although some genes involved in the metabolic regulation of the ripening process have been functionally characterized, some of the most studied genes correspond to transcription factors. High throughput transcriptomics analyses performed in strawberry red receptacle (Fragaria x ananassa) allowed us to identify a ripening-related gene that codes an atypical HLH (FaPRE1) with high sequence homology with the PACLOBUTRAZOL RESISTANCE (PRE) genes. PRE genes are atypical bHLH proteins characterized by the lack of a DNA-binding domain and whose function has been linked to the regulation of cell elongation processes. RESULTS FaPRE1 sequence analysis indicates that this gene belongs to the subfamily of atypical bHLHs that also includes ILI-1 from rice, SlPRE2 from tomato and AtPRE1 from Arabidopsis, which are involved in transcriptional regulatory processes as repressors, through the blockage by heterodimerization of bHLH transcription factors. FaPRE1 presented a transcriptional model characteristic of a ripening-related gene with receptacle-specific expression, being repressed by auxins and activated by abscisic acid (ABA). However, its expression was not affected by gibberellic acid (GA3). On the other hand, the transitory silencing of FaPRE1 transcription by agroinfiltration in receptacle produced the down-regulation of a group of genes related to the ripening process while inducing the transcription of genes involved in receptacle growth and development. CONCLUSIONS In summary, this work presents for the first time experimental data that support an important novel function for the atypical HLH FaPRE1 during the strawberry fruit ripening. We hypothesize that FaPRE1 modulates antagonistically the transcription of genes related to both receptacle growth and ripening. Thus, FaPRE1 would repress the expression of receptacle growth promoting genes in the ripened receptacle, while it would activate the expression of those genes related to the receptacle ripening process.

中文翻译：

---

非典型的HLH转录调节子在草莓成熟的容器中起着新颖而重要的作用。

背景技术在软水果中，许多基因在发育和成熟过程中的差异表达是改变其感官特性的原因。在草莓果实中，尽管已经对一些涉及成熟过程的代谢调控的基因进行了功能表征，但一些研究最多的基因与转录因子相对应。在草莓红色容器（Fragaria x ananassa）中进行的高通量转录组学分析使我们能够鉴定出与成熟相关的基因，该基因编码与PACLOBUTRAZOL RESISTANCE（PRE）基因具有高度序列同源性的非典型HLH（FaPRE1）。PRE基因是非典型的bHLH蛋白，其特征在于缺少DNA结合结构域，其功能与细胞伸长过程的调节有关。结果FaPRE1序列分析表明，该基因属于非典型bHLHs的亚家族，还包括水稻的ILI-1，番茄的SlPRE2和拟南芥的AtPRE1，它们通过抑制bHLH转录的异源二聚化而参与了转录调控过程，成为阻遏物。因素。FaPRE1呈现了一个成熟的相关基因的转录模型，该基因具有容器特异的表达，被植物生长素抑制，并被脱落酸（ABA）激活。但是，其表达不受赤霉素（GA3）的影响。另一方面，通过农杆菌浸入容器中的FaPRE1转录而使转录暂时沉默，导致与成熟过程相关的一组基因下调，同时诱导了涉及容器生长和发育的基因的转录。结论总之，这项工作首次提供了实验数据，这些数据支持非典型HLH FaPRE1在草莓果实成熟过程中的重要新功能。我们假设FaPRE1拮抗性地调节与容器生长和成熟相关的基因的转录。因此，FaPRE1将抑制成熟的容器中促进容器生长的基因的表达，同时其将激活与容器成熟过程相关的那些基因的表达。