Low temperatures are the most significant abiotic stressor for the conservation and production of Phalaenopsis in non-tropical areas. CBF/DREB1 transcription factors play an important role in the plant abiotic stress response. In this study, 31 DREB family members were identified in the Phalaenopsis genome. Expression pattern analysis showed that the expression of different PaDREB members varied among tissue sites. PaDREB1D was isolated from Phalaenopsis aphrodite, and multiple sequence alignment showed that PaDREB1D belonged to the A1 subgroup of the DREB family and was localized in the nucleus. PaDREB1D overexpression in protocorm-like bodies of Phalaenopsis reduced cell damage during low-temperature stress, increased antioxidant enzyme activity, and enhanced the low-temperature tolerance of protocorm-like bodies. The results of this study provide a theoretical basis for breeding for cold resistance and investigating the molecular mechanisms related to low-temperature responses in Phalaenopsis.

Soft rot caused by Dickeya fangzhongdai is a destructive disease in Phalaenopsis production that seriously impacts the quality and yield of Phalaenopsis. To explore the molecular mechanisms underlying disease resistance, transcriptome analysis was conducted on resistant and susceptible Phalaenopsis varieties. By comparing the transcriptomes of the resistant variety ‘ES L20’ and the susceptible variety ‘Zishuijing’ after D. fangzhongdai infection, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed. The results revealed that the differentially expressed genes were mainly enriched in pathways related to plant–pathogen interaction, plant hormone signal transduction, and the phenylpropanoid biosynthetic pathway. In the resistant variety ‘ES L20’, some genes in the Ca²⁺ pathway, PAMP-triggered immunity pathway, and Effector-triggered immunity pathway were significantly up-regulated. Analysis of the transcriptome levels of genes in the phytohormone-related pathways showed that genes associated with IAA (indole-3-acetic acid), salicylic acid, and jasmonic acid signal transduction pathways were all up-regulated in the resistant variety after inoculation. Furthermore, the analysis of genes in the phenylpropanoid biosynthesis pathway demonstrated significant up-regulation in the resistant variety. The determination of lignin content validated this result, confirming the crucial role of lignin synthesis in Phalaenopsis defense against soft rot. These findings suggest that the differentially expressed genes in phytopathogenic interaction pathways, along with those involved in hormone-related and lignin synthesis pathways, play important roles in Phalaenopsis resistance to soft rot. This study provides valuable insights into the molecular basis of Phalaenopsis resistance to soft rot and may contribute to the development of effective disease control strategies.