Chimonanthus praecox (wintersweet) is highly valued ornamentally and economically. Floral bud dormancy is an important biological characteristic in the life cycle of wintersweet, and a certain period of chilling accumulation is necessary for breaking floral bud dormancy. Understanding the mechanism of floral bud dormancy release is essential for developing measures against the effects of global warming. miRNAs play important roles in low-temperature regulation of flower bud dormancy through mechanisms that are unclear. In this study, small RNA and degradome sequencing were performed for wintersweet floral buds in dormancy and break stages for the first time. Small RNA sequencing identified 862 known and 402 novel miRNAs; 23 differentially expressed miRNAs (10 known and 13 novel) were screened via comparative analysis of breaking and other dormant floral bud samples. Degradome sequencing identified 1707 target genes of 21 differentially expressed miRNAs. The annotations of the predicted target genes showed that these miRNAs were mainly involved in the regulation of phytohormone metabolism and signal transduction, epigenetic modification, transcription factors, amino acid metabolism, and stress response, etc., during the dormancy release of wintersweet floral buds. These data provide an important foundation for further research on the mechanism of floral bud dormancy in wintersweet.

Superoxide dismutase (SOD) enzymes are essential for reducing oxidative damage resulting from overabundant reactive oxygen species under abiotic stress. While the SOD gene family has been extensively studied in many species, research focusing on Cymbidium species remains limited. In this study, a comprehensive analysis of the SOD gene family in three Cymbidium genomes was conducted. A total of 23 SOD genes were identified, with nine SODs in C. sinense, eight in C. ensifolium, and six in C. goeringii. These SOD genes were categorized into three clades: Cu/Zn-SOD, Fe-SOD, and Mn-SOD, with the Cu/Zn-SOD being the most abundant in these three types. This classification was supported by analyses of conserved domains, motifs, and phylogenetic relationships. Cis-element prediction showed that stress-responsive elements were identified in most SODs. Transcriptomic data revealed that seven CsSODs exhibited a border expression in all sequenced tissues, while two exhibited undetectable expression levels. Further qRT-PCR analysis showed that all CsSODs were upregulated under salt stress, with some exhibiting significant changes in expression. These findings all highlight the crucial role of CsSODs in the salt stress response and provide valuable insights for further breeding salt-tolerance varieties of C. sinense.

As a highly valued orchid species, Cymbidium ensifolium (C. ensifolium) exhibits a natural flowering period mainly from July to September, which does not align with the market demand and shows low flowering quality, thereby significantly constraining the development of the C. ensifolium floriculture industry. To address this key issue, the study used C. ensifolium ‘Longyan Su’ as the experimental material, with white light as the control and composite light with varying ratios of red and blue light as the treatments, and investigated the influence of light quality on flowering. The results showed that blue light could significantly advance the flowering time, while red light could markedly improve the flower quality. Blue light promoted the accumulation of soluble protein and soluble sugar during flower bud differentiation, while red light enhanced their accumulation during floral organ development. During the flower bud differentiation and development stage, blue light increased the synthesis of abscisic acid (ABA) in leaves, and red light promoted the production of gibberellic acid (GA₃) and zeatin riboside (ZR). The study provides an important foundation and reference for further analysis of the flowering mechanism of C. ensifolium under different light quality treatments, and also provides technical support for flowering regulation of orchids in practical production.