Dendrobium catenatum possesses special survival strategy including facultative crassulacean acid metabolism (CAM) to cope with various environmental stresses. The homeodomain-leucine zipper (HD-Zip) proteins had been reported to play essential roles in adaption to the environment. However, the role of the HD-Zip gene family in stresses responses and drought-induced facultative CAM in D. catenatum was largely unknown. In this study, 35 HD-Zip genes were identified in D. catenatum (DcHDZs), and were phylogenetically grouped into four subfamilies, which was further supported by the analysis of their conserved motifs and structures. Expression profile analysis of DcHD-Zip genes based on public transcriptomic data and qRT-PCR showed that most DcHD-Zip genes showed biased expression in leaf and flower than in stem and root. Three DcHD-Zip genes denominated as DcHDZ04, DcHDZ20 and DcHDZ22 belong to HD-Zip I and II subfamilies, were induced significantly under high light, low light, salt and heat stresses. Moreover, we found that the plant hormone biosynthesis and signal transduction played a vital role in facultative CAM of D. catenatum under drought, especially ABA. Nine DcHD-Zip genes were identified as DEGs and showed close relationship with several genes involved in plant hormone biosynthesis and signal transduction, suggesting their important roles in drought-induced facultative CAM of D. catenatum. This systematic analysis provided a foundation for further functional characterization of HD-Zip genes and also revealed an important regulation mechanism of facultative CAM in D. catenatum.

铁皮石end拥有特殊的生存策略，包括兼职的颅骨石蜡酸代谢（CAM）以应对各种环境压力。据报道，同源域-亮氨酸拉链（HD-Zip）蛋白在适应环境中起着至关重要的作用。但是，HD-Zip基因家族在应激反应和干旱诱导的链状线虫CAM中的作用在很大程度上是未知的。在这项研究中，在链状线虫（DcHDZs）中鉴定了35个HD-Zip基因，并在系统发育上分为四个亚科，这通过对其保守基序和结构的分析得到进一步支持。DcHD-Zip的表达谱分析基于公开转录组数据和qRT-PCR的基因显示，大多数DcHD-Zip基因在叶和花中的表达偏向于茎和根。在强光，弱光，盐和热胁迫下，分别诱导了三个分别命名为DcHDZ04，DcHDZ20和DcHDZ22的DcHD-Zip基因，分别属于HD-Zip I和II亚科。此外，我们发现植物激素的生物合成和信号转导在干旱，尤其是ABA下对链状线虫的兼性CAM起着至关重要的作用。九个DcHD-Zip这些基因被鉴定为DEGs，并与参与植物激素生物合成和信号转导的几个基因密切相关，表明它们在干旱诱导的链状线虫CAM中起着重要的作用。该系统分析为HD-Zip基因的进一步功能表征奠定了基础，并揭示了链状线虫兼性CAM的重要调控机制。