Cymbidium sinense represents a distinctive Orchidaceae plant that is more tolerant than other terrestrial orchids. Studies have shown that many members of the MYB transcription factor (TF) family, especially the R2R3-MYB subfamily, are responsive to drought stress. This study identified 103 CsMYBs; phylogenetic analysis classified these genes into 22 subgroups with Arabidopsis thaliana. Structural analysis showed that most CsMYB genes contained the same motifs, three exons and two introns, and showed a helix-turn-helix 3D structure in each R repeat. However, the members of subgroup 22 contained only one exon and no intron. Collinear analysis revealed that C. sinense had more orthologous R2R3-MYB genes with wheat than A. thaliana and rice. Ka/Ks ratios indicated that most CsMYB genes were under purifying negative selection pressure. Cis-acting elements analysis revealed that drought-related elements were mainly focused on subgroups 4, 8, 18, 20, 21, and 22, and Mol015419 (S20) contained the most. The transcriptome analysis results showed that expression patterns of most CsMYB genes were upregulated in leaves in response to slight drought stress and downregulated in roots. Among them, members in S8 and S20 significantly responded to drought stress in C. sinense. In addition, S14 and S17 also participated in these responses, and nine genes were selected for the real-time reverse transcription quantitative PCR (RT-qPCR) experiment. The results were roughly consistent with the transcriptome. Our results, thus, provide an important contribution to understanding the role of CsMYBs in stress-related metabolic processes.

Endophytic fungi enhance plant growth and stress resilience, yet their molecular roles in the roots of the endangered tree Phoebe bournei remain unclear. A comparative RNA-seq analysis was performed on root transcriptomes from wild, endophyte-colonized adult trees (OT) and axenically grown seedlings (ST). Unmapped reads were analyzed against the NCBI nucleotide (NT) database using BLASTN (v2.17.0), revealing Rhizophagus irregularis as the predominant endophytic fungus. Differential expression analysis identified 5891 DEGs, which were significantly enriched in pathways related to plant–pathogen interactions, phenylpropanoid biosynthesis, plant hormone signal transduction, and MAPK signaling. Key upregulated genes included PbMPK3, PbCML42, PbCML41.2, and PbGSTU28, suggesting enhanced ROS scavenging, calcium signaling, and defense activation. RT-qPCR validation confirmed the transcriptomic trends for selected genes. Our findings reveal that root endophytic fungi modulate a coordinated network involving immune priming, phytohormone regulation, and redox homeostasis, thereby supporting root development and enhancing resistance to biotic and abiotic stresses in P. bournei. This study provides foundational molecular insights into beneficial plant–endophyte interactions and identifies candidate genes that are valuable for the conservation and breeding of this threatened species.

The MADS-box transcription factor gene family is essential for the differentiation and development of floral organs. Genome-wide and transcriptome data from Phoebe bournei provide the foundation for studying its floral development. In this study, phylogenetic relationships, protein characteristics, conserved domains, gene structures, and cis-acting elements in promoter regions of P. bournei MADS-box genes were systematically analyzed through bioinformatics methodologies. A total of 69 PbMADS genes were identified and classified into 15 subfamilies based on their phylogenetic relationships. The potential functions of these genes were inferred based on transcriptomic data and GO classification. In addition, we selected genes from the ABCDE model to analyze protein interactions and performed RT-qPCR to analyze their expression in each floral organ whorl (outer tepals, inner tepals, stamens, and carpel). Based on these analyses, we rationally constructed a model for the floral organ development in P. bournei. This study, thus, provides a theoretical reference for germplasm innovation in P. bournei and offers insights into the floral development in other Lauraceae species.

Adventitious root formation in stem cuttings of Phoebe bournei, an economically and ecologically significant woody species, is a major bottleneck in clonal propagation. To elucidate the impact of spectral quality on early adventitious root development, we characterized the morphological, hormonal, and transcriptomic dynamics of primordium initiation and differentiation under white, red, and blue light. Under red light, cuttings exhibited the earliest and most pronounced formation of white filamentous structures at lenticels, indicative of root primordium initiation, as early as 20 days after cutting, whereas white and blue light treatments showed delayed responses. Paraffin section analysis confirmed the induced origin of root primordia from cortical and vascular cambial tissues, with red light accelerating their differentiation. Hormonal profiling revealed that although red and blue light transiently increased indole-3-acetic acid levels in the basal bark, the persistently elevated abscisic acid in apical buds across all treatments likely suppressed polar auxin transport. Notably, red light downregulated brassinosteroid and gibberellin levels in the base, which could alleviate growth inhibition. Transcriptome analysis of phloem tissues identified significant differential expression of auxin-responsive genes, including members of the ARF (e.g., PbARF6, PbARF13), GH3, and SAUR gene families, which were specifically upregulated under red light. Collectively, our findings suggest that red light accelerates the early induction and differentiation of adventitious root primordia in P. bournei cuttings by modulating hormonal homeostasis and activating key auxin signaling pathways. This work provides a physiological and molecular basis for optimizing light conditions in the vegetative propagation of P. bournei.