# Drought Stress Induced Different Response Mechanisms in Three Dendrobium Species under Different Photosynthetic Pathways

## TL;DR

This study explores how three Dendrobium species respond to drought stress by changing their photosynthetic pathways, revealing molecular mechanisms that improve drought tolerance.

## Contribution

The study identifies PEPC gene variations and miRNA regulation linked to the shift from C3 to CAM photosynthesis in Dendrobium under drought stress.

## Key findings

- Transcriptome analysis revealed numerous differentially expressed genes (DEGs) involved in drought response mechanisms.
- Phylogenetic and expression analysis showed PEPC gene variations under drought stress, linked to photosynthetic pathway shifts.
- Upregulation of Dc_gene2609 by dof-miR-384 may enhance drought tolerance by promoting CAM photosynthesis.

## Abstract

Many Dendrobium species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing droughts. However, the molecular mechanisms underlying the shift in the photosynthetic pathway induced by drought remain unclear. To address this issue, three Dendrobium species with different photosynthetic pathways were selected for sequencing and transcriptome data analysis after drought treatment. The findings included 134.43 GB of sequencing data, with numerous Differentially Expressed Genes (DEGs) exhibiting different response mechanisms under drought stress. Gene Ontology (GO)–KEGG-based enrichment analysis of DEGs revealed that metabolic pathways contributed to drought tolerance and alterations in photosynthetic pathways. Phosphoenolpyruvate Carboxylase (PEPC) was subjected to phylogenetic tree construction, sequence alignment, and domain analysis. Under drought stress, variations were observed in the PEPC gene structure and expression among different Dendrobium species; the upregulation of Dc_gene2609 expression may be caused by dof-miR-384, which resulted in the shift from C3 photosynthesis to CAM, thereby improving drought tolerance in Dendrobium. This study revealed the expression patterns and roles of PEPC genes in enhancing plant drought tolerance and will provide an important basis for in-depth research on Dendrobium’s adaptation mechanisms in arid environments.