Dehydration response element binding factor (DREB) is a family of plant-specific transcription factors, whose members participate in the regulation of plant responses to various abiotic stresses. Prunus nana, also known as the wild almond, is a member of the Rosaceae family that is rare and found to grow in the wild in China. These wild almond trees are found in hilly regions in northern Xinjiang, and exhibit greater drought and cold stress resistance than cultivated almond varieties. However, the response of P. nana DREBs (PnaDREBs) under low temperature stress is still unclear. In this study, 46 DREB genes were identified in the wild almond genome, with this number being slightly lower than that in the sweet almond (Prunus dulcis cultivar ‘Nonpareil’). These DREB genes in wild almond were separated into two classes. All PnaDREB genes were located on six chromosomes. PnaDREB proteins that were classified in the same groups contained specific shared motifs, and promoter analyses revealed that PnaDREB genes harbored a range of stress-responsive elements associated with drought, low-temperature stress, light responsivity, and hormone-responsive cis-regulatory elements within their promoter regions. MicroRNA target site prediction analyses also suggested that 79 miRNAs may regulate the expression of 40 of these PnaDREB genes, with PnaDREB2. To examine if these identified PnaDREB genes responded to low temperature stress, 15 of these genes were selected including seven homologous to Arabidopsis C-repeat binding factor (CBFs), and their expression was assessed following incubation for 2 h at 25 °C, 5 °C, 0 °C, −5 °C, or −10 °C. In summary, this analysis provides an overview of the P. nana PnaDREB gene family and provides a foundation for further studies of the ability of different PnaDREB genes to regulate cold stress responses in almond plants.

Styrax japonicus is a small ornamental tree with medicinal value. An S. japonicus variety with purplish red calyxes and white petals has higher ornamental value. The mechanism underlying calyx pigmentation in S. japonicus is still unclear. In this study, metabolome data combined with transcriptome profiling were used to explore the molecular mechanisms underlying the difference in the color of calyx in two varieties of S. japonicus, namely, Red Linglong (RA; purplish red calyx) and Green Linglong (GA; green calyx). The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that the levels of delphinidin 3,5-diglucoside, delphinidin 3-O-glucoside, and malvidin 3-O-glucoside when enriched in delphinidin biosynthesis were significantly higher in the RA calyx than in the GA calyx. These key differentially accumulated metabolites were highly correlated with five late biosynthetic genes that were enriched in the anthocyanin biosynthesis pathway. MYB1, MYB82, and MYB113 were the three probable transcription factors responsible for anthocyanin accumulation. This study provides novel insights into secondary metabolism pathways, their regulators, and the changes in the transcription and metabolite levels in the calyx of S. japonicus regulating sepal color. The results provide a theoretical basis for exploring the mechanism of calyx color formation in S. japonicus and provide genetic material and a reference for molecular breeding to obtain desired flower colors in the future.