Background: Tissue culture is one of the most important methods for propagating orchids. Notably, many orchid seedlings exhibit autonomous flowering during the cultivation process. To explore the underlying mechanism, Anoectochilus roxburghii (Wall.) Lindl., an orchid that spontaneously forms in vitro flowers, was analyzed in this study. Methods: Bud samples at the early, middle, and fully open stages were collected for transcriptome sequencing, followed by differential expression, trend, enrichment and protein–protein interaction (PPI) network analyses. Results: Differential gene expression analysis identified 2364, 4137, and 6522 differentially expressed genes (DEGs) in the early vs. middle, middle vs. open, and early vs. open comparisons, respectively. These DEGs were significantly enriched in various metabolic and biosynthetic pathways, particularly in ko01100 (metabolic pathways). PPI network analysis further identified hub genes, including MCM3, MCM4, and MCM7, which are associated with DNA replication, and CURL3, which is linked to plant hormone signal transduction pathways. Conclusion: Our findings provide novel insights into the molecular mechanisms driving in vitro flowering in A. roxburghii, highlighting the importance of metabolic and biosynthetic process signaling in this unique developmental transition. These results provide valuable resources for future studies on orchid propagation and floral development.

In recent years, the market for succulent plants has experienced rapid growth. To increase the yield and value of Echeveria laui, a member of the succulent family, a tissue culture method was established in this study. The highest callus induction rate (26.7%) was achieved on Murashige and Skoog (MS) medium supplemented with 3 mg·L⁻¹ 6-benzylaminopurine (6-BA), 1 mg·L⁻¹ α -naphthaleneacetic acid (NAA), and 0.1 mg·L⁻¹ thidiazuron (TDZ). The highest proliferation coefficient (4.26) was observed on medium containing 3 mg·L⁻¹ 6-BA and 1 mg·L⁻¹ NAA. Seedlings were regenerated when calli were cultured on MS or 1/2 MS medium without plant growth regulators (PGRs). During proliferation, three distinct types of calli were identified and analyzed using morphological observations and widely targeted metabolomics. Morphological analysis revealed that regenerable calli (GCs) presented numerous granular buds on their surface, and the cells were regular and complete, contributing to their regenerability. Metabolomic analysis revealed that the differentially accumulated metabolites (DAMs) were primarily amino acids and their derivatives, with dUMP identified as a biomarker for dis- tinguishing among the three callus types. Additionally, changes in phytohormone levels were observed across the different callus types. These findings provide a valuable reference for optimizing culture systems, minimizing undesirable tissue changes, and enhancing propagation efficiency.

A new orchid species, Bulbophyllum versicolor (Malaxideae, Epidendroideae, Orchidaceae), from Malipo, Yunnan, China, is described and illustrated here. Detailed morphological study indicates that B. versicolor is similar to B. japonicum, but it differs in the shape and size of leaf and flower and flower colour. Molecular analyses based on the nuclear ribosomal DNA (nrITS) and plastid DNA (matK, atpI-atpH and trnL-F) reveal that B. versicolor is a new species and genetically similar to B. japonicum.