The basic helix-loop-helix (bHLH) transcription factor family is the second-largest family in plants, where it plays essential roles in development, and the responses to multiple abiotic and biotic stressors. However, little information is available about this gene family in Prunus mume, which is widely cultivated in East Asia as an ornamental fruit tree. Here, 100 PmbHLH genes were identified, and their evolution and functions were explored in P. mume for the first time. The PmbHLH genes were classified into 21 subfamilies. The chromosomal distribution, physicochemical properties, bHLH domain, conserved motif, and intron/exon compositions were also analyzed. Furthermore, the evolutionary pattern, divergence time of the PmbHLH family, and genetic relationships among P. mume, Arabidopsis thaliana, and Prunus persica and Fragaria vesca of Rosaceae were explored. The functional prediction analysis of these PmbHLHs indicated that their functions varied, and included participating in the formation of organs and tissues, responding to stress, and the biosynthesis and metabolism of hormones and other secondary metabolites. Interestingly, expression analyses of PmbHLHs also revealed diverse expression patterns. Most of the PmbHLH genes were highly expressed in roots and stems, and a few were highly expressed in leaves, buds, and fruits, indicating tissue expression specificity. Eight PmbHLH genes, which were upregulated during low-temperature stress, may have critical roles in the response to cold stress. Ten PmbHLHs were differentially expressed between weeping and upright branches in a P. mume F₁ population. These results shed light on the structure and evolution of the PmbHLH gene family, and lay a foundation for further functional studies of the bHLH genes.

基本螺旋-环-螺旋 ( bHLH ) 转录因子家族是植物中的第二大家族，它在植物的发育以及对多种非生物和生物胁迫的反应中发挥着重要作用。然而，关于Prunus mume中该基因家族的信息很少，该基因家族在东亚被广泛种植，作为观赏果树。在这里，鉴定了100个PmbHLH基因，并首次在P. mume中探索了它们的进化和功能。PmbHLH _基因被分为21个亚科。还分析了染色体分布、理化性质、bHLH 结构域、保守基序和内含子/外显子组成。此外，还探讨了蔷薇科P. mume、拟南芥、Prunus persica和Fragaria vesca的进化模式、分化时间以及PmbHLH家族的遗传关系。对这些PmbHLHs的功能预测分析表明，它们的功能各不相同，包括参与器官和组织的形成、对压力的反应以及激素和其他次生代谢物的生物合成和代谢。有趣的是， PmbHLHs的表达分析还揭示了不同的表达模式。PmbHLH基因大部分在根和茎中高表达，少数在叶、芽和果实中高表达，具有组织表达特异性。八个在低温胁迫期间上调的PmbHLH基因可能在对冷胁迫的反应中起关键作用。在P. mume F ₁种群中， 10个 PmbHLH在垂枝和直立枝之间有差异表达。这些结果揭示了PmbHLH基因家族的结构和进化，为进一步研究bHLH基因的功能奠定了基础。