Soluble sugars are key determinants of fruit quality, contributing to the desirable flavors of fruit crops such as peach. Our previous research identified PpERDL16 (early response to dehydration 6-like) as a negative regulator of fructose content in peach fruits. The current study identifies six ERD-like genes and classifies them into four subfamilies through bioinformatics and gene expression analyses. All six genes contain sugar transporter domains and are localized to the tonoplast, confirmed by subcellular localization assays in tobacco. The expression analysis undertaken during fruit development revealed that the genes PpERDL6-1 (previously as PpERDL16), PpERDL6-2 and PpERDL6-3 were highly expressed during the early stages of fruit ripening, with PpERDL6-1 showing a marked downregulation during the late ripening stage. Functional assays demonstrated functional divergence for these genes in sugar modulation: transient overexpression of PpERDL6-1 significantly reduced fructose and glucose levels, whereas overexpression of PpERDL6-2 specifically increased glucose levels in mesocarp slices. Additionally, overexpression of PpERDL6-3, PpERDL6-4, and PpERDL6-6 led to enhanced fructose accumulation. Further, Promoter motif analysis indicated that all six ERD6-like genes are responsive to light and hormonal stimuli related to abiotic stress. Under drought treatment, soluble sugars (glucose, fructose and sucrose) accumulated significantly, and expression of all six genes was fluctuated. In conclusion, our findings highlight the pivotal roles of the ERD6-like gene family in regulating soluble sugar accumulation, suggesting their involvement in the coordination of peach fruit sweetness and stress response. This study offers novel insights into the molecular mechanisms that underpin fruit quality improvement under abiotic stress conditions.

The TCP (Teosinte branched 1/Cycloidea/Proliferating) gene family comprises plant-specific transcription factors essential for regulating growth, development, and environmental adaptation. Utilizing the high-quality ‘Rui Youpan 1’ (‘RYP1’) reference genome, we conducted a comprehensive genome-wide identification and characterization of the TCP family in peach (Prunus persica). We identified 20 PpTCP genes and systematically evaluated their physicochemical properties, chromosomal distribution, phylogeny, gene architecture, and promoter cis-regulatory elements. Notably, the enrichment of abscisic acid-responsive elements (ABREs) in their promoters suggests a significant role in abiotic stress signaling. Integrated RNA-seq and RT-qPCR analyses identified six putative candidates (PpTCP3, 5, 6, 11, 14, and 15) with pronounced differential expression under drought conditions. Subcellular localization confirmed that all tested PpTCPs function within the nucleus. Moreover, the results of STRING-based computer simulations predicting protein–protein interactions indicate that PpTCP3 and PpTCP5 interact with key hormone pathways and stress-related transcription factors (TFs), including auxin signaling and strigolactone signaling.