Basic helix-loop-helix (bHLH) is the second largest family of transcription factors that widely exist in plants and animals, and plays a key role in a variety of biological processes. As an important forage crop worldwide, little information is available about the bHLH family in orchardgrass (Dactylis glomerata L.), although a huge number of bHLH family have been identified and characterized in plants. In this study, we performed genome-wide analysis of bHLH transcription factor family of orchardgrass and identified 132 DgbHLH genes. The phylogenetic tree was constructed by using bHLH proteins of orchardgrass, with Arabidopsis thaliana and Oryza sativa bHLH proteins, to elucidate their homology and classify them into 22 subfamilies. The results of conserved motifs and gene structure support the classification of DgbHLH family. In addition, chromosomal location and gene duplication events of DgbHLH genes were further studied. Transcriptome data exhibited that DgbHLH genes were differentially expressed in different tissues of orchardgrass. We analyzed the gene expression level of 12 DgbHLH genes in orchardgrass under three types of abiotic stresses (heat, salt, and drought). Finally, heterologous expression assays in yeast indicated that DgbHLH46 and DgbHLH128 may enhance the resistance to drought and salt stress. Furthermore, DgbHLH128 may also be involved in abiotic stress by binding to the MYC element. Our study provides a comprehensive assessment of DgbHLH family of orchardgrass, revealing new insights for enhancing gene utilization and improving forage performance.

碱性螺旋-环-螺旋（bHLH）是广泛存在于动植物体内的第二大转录因子家族，在多种生物过程中起着关键作用。作为世界范围内重要的牧草作物，关于果园草（ Dactylis glomerata L.）中bHLH家族的信息很少，尽管已经在植物中鉴定和表征了大量bHLH家族。在这项研究中，我们对果园草的 bHLH 转录因子家族进行了全基因组分析，并鉴定了 132个 DgbHLH基因。使用果园草的 bHLH 蛋白与拟南芥和水稻的bHLH蛋白构建系统发育树，以阐明它们的同源物y 并将它们分为 22 个亚科。保守基序和基因结构的结果支持 DgbHLH 家族的分类。此外，进一步研究了DgbHLH基因的染色体定位和基因复制事件。转录组数据显示DgbHLH基因在果园草的不同组织中差异表达。我们分析了三种非生物胁迫（热、盐和干旱）下果园草中 12 个DgbHLH基因的基因表达水平。最后，酵母中的异源表达测定表明DgbHLH46和DgbHLH128可以增强对干旱和盐胁迫的抵抗力。此外，DgbHLH128也可能通过与 MYC 元件结合而参与非生物胁迫。我们的研究对果园草的 DgbHLH 家族进行了全面评估，揭示了增强基因利用和改善牧草性能的新见解。