Transcriptome analysis of substrate temperature effects on adventitious root formation in peach rootstocks

The propagation of peach rootstocks, particularly adventitious root (AR) formation, is influenced by multiple factors, with substrate temperature being crucial. This experiment studied the differential gene expression patterns of GF677 rootstock cuttings treated with 200 mg L^-1 indole-3-butyric acid (IBA) under various substrate temperatures (ambient temperature (CK), 19 °C, 22 °C, 25 °C, and 28 °C) and cutting periods (7, 14, and 21 days). The results showed a maximum rooting rate of 91% when assessed at 40 days under 25 °C, while RNA sequencing was performed at earlier stages (7, 14, and 21 days). The highest number of differentially expressed genes (DEGs) observed between 22-25 °C. Therefore, the optimal substrate temperature for propagation was determined to be 25 °C. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis highlighted "starch and sucrose metabolism (photosynthesis processes)" and "plant hormone signal transduction (especially auxin)" as enriched pathways. Specifically, 26 plant genes (ARFs, LBDs, SAURs, and GH3) and 22 AR formation-related genes (AUR3, LRP1, RGF1, AIR9, AP2, and NAC) were identified from these DEGs. Weighted gene co-expression network analysis (WGCNA) clarified the involvement of various transcription factors (WRKYs, ERFs, NACs, bHLHs, bZIPs, and MYBs) in AR formation. These findings indicate significant differences in gene expression under different combinations of substrate temperatures and cutting periods. Overall, this study enhances our understanding of the molecular mechanisms underlying peach rootstocks asexual reproduction.