Genome-wide identification and expression analysis of stress-associated proteins (SAPs) containing A20/AN1 Zinc finger in Dendrobium officinale

Stress-associated proteins (SAPs) are zinc finger proteins involved in the regulation of various stresses in a variety of plant species. Less is known about their characteristics and molecular functions in Dendrobium officinale, which is a traditional Chinese medicinal herb. Here, 18 DoSAPs with conserved zinc-binding motifs were identified in D. officinale. The phylogenetic analysis of these proteins and their orthologs from Arabidopsis and rice indicated that they can be classified into six of the nine groups within the SAP gene family. Genes within the same group exhibit similar structures and conserved domains. An examination of the cis-acting elements in the DoSAP promoters identified numerous elements related to stress and plant hormones, particularly those responsive to light. Predictive modeling of the three-dimensional structures and ligand-binding sites of DoSAP proteins revealed that most possess the typical Cys2His2 zinc finger motif. High-throughput RNA-seq data showed that DoSAP gene profiles differed among various tissues. Furthermore, DoSAP gene expression is altered in response to various stresses (salt, drought, heat, cold and light) and phytohormone treatments (GA, ABA), suggesting that the transcriptional regulation of DoSAP genes may play a crucial role, especially in their significant response to light treatment. Notably, DoSAP3 (light/salt stress), DoSAP4 (different tissues/growth), DoSAP8 (temperature stress) exhibit significantly high expression. This investigation systematically characterized DoSAP genes and laid a solid foundation for understanding their functional diversification in mediating D. officinale's adaptation to environmental stresses responses.