The artificial enlargement of the planting area and ecological amplitude of ornamentals for horticultural and landscape applications are significant. Herbaceous peony (Paeonia lactiflora Pall.) is a world-famous ornamental with attractive and fragrant flowers and is mainly planted in temperate and cool areas. Comparatively higher winter temperatures in the subtropical and tropical Northern Hemisphere result in a deficit of chilling accumulation for bud dormancy release, which severely hinders “The southward plantation of herbaceous peony”. Studies on the dormancy, chilling requirement (CR) and relevant molecular mechanisms of peony are needed to enhance our ability to extend the range of this valuable horticultural species. Based on natural and artificial chilling experiments, and chilling hour (CH) and chilling unit (CU) evaluation systems, the lowest CR of ‘Hang Baishao’ was between 504.00 and 672.00 CHs and the optimal CR was 672.00 CHs and 856.08 CUs for achieving strong sprouting, growth and flowering performance. Transcriptome sequencing and gene identification by RNA-Seq were performed on ‘Hang Baishao’ buds during the dormancy and sprouting periods. Six gene libraries were constructed, and 66 temperature- and photoperiod-associated unigenes were identified as the potential candidate genes that may regulate or possibly determine CR characteristics. The difference in the expression patterns of SUPPRESSPOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) between the winters of 2012–2013 and 2015–2016, and the difference of CR fulfillment periods also between these two winters represented the interesting congruent relationships. This correlation was also observed for WRKY DNA-BINDING PROTEIN 33 (WRKY 33). Combined with the results acquired from all of experiments, ‘Hang Baishao’ was confirmed to be a superb peony resource that have significantly low CR characteristics. The two genes of SOC1 and WRKY33 are likely involved in determining the CR amount and fulfillment period of ‘Hang Baishao’. HEAT SHOCK PROTEIN, OSMOTIN and TIMING OF CAB EXPRESSION 1 also deserve attention for the CR research. This study could contribute to the knowledge of the deep factors and mechanisms that regulate CR characteristics, and may be beneficial for breeding new germplasms that have low CRs for landscape or horticulture applications in subtropical regions.

The plant-specific transcription factor TEOSINTE BRANCHED, CYCLOIDEA, AND PROLIFERATING CELL FACTOR (TCP) gene family plays vital roles in various biological processes, including growth and development, hormone signaling, and stress responses. However, there is a limited amount of information regarding the TCP gene family in roses (Rosa sp.). In this study, we identified 18 TCP genes in the rose genome, which were further classified into two subgroups (Group A and Group B) via phylogenetic analysis. Comprehensive characterization of these TCP genes was performed, including gene structure, motif composition, chromosomal location, and expression profiles. Synteny analysis revealed that a few TCP genes are involved in segmental duplication events, indicating that these genes played an important role in the expansion of the TCP gene family in roses. This suggests that segmental duplication events have caused the evolution of the TCP gene family and may have generated new functions. Our study provides an insight into the evolutionary and functional characteristics of the TCP gene family in roses and lays a foundation for the future exploration of the regulatory mechanisms of TCP genes in plant growth and development.

Lonicera japonica is a well-known medicinal plant, and the Damaohua cultivar is one of the oldest known honeysuckle cultivars in China. The 155,151 bp chloroplast genome of this cultivar was obtained through Illumina sequencing. The genome includes a pair of inverted repeats (IRa and IRb; 23,789 bp each), a large single-copy region (88,924 bp), and a small single-copy (SSC) region (18,649 bp). In total, 127 unique genes were identified: 80 protein-coding, 39 tRNA, and 8 rRNA genes. Only ycf3 contained two introns. Eighty-nine large repetitive sequences and 54 simple sequence repeats were detected. Fifty potential RNA editing sites were predicted. Adaptive evolution analysis revealed that infA, matK, petB, petD, rbcL, rpl16, rpl2, rps3, ycf1, and ycf2 were positively selected, possibly reflecting the specific environmental adaptations of this cultivar. Sequence alignment and analysis revealed several candidate fragments for Lonicera species identification, such as the intergenic regions rpoB-petN, rbcL-accD, and psaA-ycf3. The IR region boundary and phylogenetic analysis revealed that the L. japonica cv. Damaohua chloroplast genome was most closely related to the L. japonica genome, but there were five distinct differences between the two. There are four sites with high variability between L. japonica and L. japonica cv. Damaohua with nucleotide variability (Pi) greater than 0.002, including rps2-rpoC2, atpB-rbcL, ycf1, and ycf1-trnN GUU. The differences between L. japonica and L. japonica cv. Damaohua were further confirmed by the single nucleotide polymorphism sites between these two species. Therefore, this study revealed that the chloroplast genome can serve as a universal super barcode for plant identification, which can identify differences and help distinguish Lonicera japonica from related species. An understanding of Lonicera japonica cv. Damaohua chloroplast genomics and a comparative analysis of Lonicera species will provide a scientific basis for breeding, species identification, systematic evolution analysis, and chloroplast genetic engineering research on medicinal honeysuckle plants.

As an endemic species and the only Helleborus species in China, Helleborus thibetanus is highly valued in medicinal and ornamental applications, and basic research is needed for its further resource conservation and utilization. Considering the interesting disjunct distribution of the genus Helleborus, we focus on the distribution pattern of H. thibetanus in this research. Based on species distribution models using three different algorithms (MaxEnt, RF, and FDA), we constructed a robust ensemble model and predicted potential distributions under different scenarios: current situation, paleo periods since the Last Glacial Maximum, and simulations of climate change in the 2070s. The habitat suitability of H. thibetanus across geography and scenarios was further analyzed by calculating regional areas and centroids. The results showed that H. thibetanus is currently distributed in southern Shaanxi and northern Sichuan, while central and southern Sichuan used to be suitable 14 thousand years ago but gradually became unsuitable, which may reflect the population decrease in Sichuan and the population expansion in Shaanxi over the last 14 thousand years. Our results showed that current populations are under limited extinction pressure in the soft climate change scenario (ssp126), but most populations in Shaanxi are under extinction pressure in the hardy situation scenario (ssp585). Fortunately, northern Sichuan is predicted to be relatively stable under climate change (both ssp126 and ssp585), and regions in western Sichuan and eastern Qinghai are predicted to become newly suitable for H. thibetanus. These findings should be helpful for the further conservation and utilization of H. thibetanus and also help us understand the history of the conjunct distribution pattern of the Helleborus genus.

Paeonia lactiflora Pall. (herbaceous peony) is a high-value ornamental and medicinal plant in China with considerable market potential. However, conventional propagation methods are limited by low multiplication rates and long production cycles, making it difficult to meet the demand for large-scale planting materials. As a key approach for rapid propagation, tissue culture techniques for P. lactiflora have achieved significant progress in recent years. This review summarizes advances in the tissue culture system for P. lactiflora over the past decade, focusing on major in vitro regeneration pathways (organogenesis and somatic embryogenesis) and crucial technical stages, including explant selection and culture environment optimization. Distinct from previous reviews that only introduce partial technical aspects of P. lactiflora tissue culture, this review comprehensively outlines the overall tissue culture system, analyses the current species-specific bottlenecks (browning, vitrification, rooting and acclimatization) with their underlying causes and proposes targeted strategies. Furthermore, future development trends are prospected by integrating emerging research directions, including molecular regulatory mechanisms and eco-adaptive breeding. This review aims to provide a theoretical foundation and technical support for obtaining propagule for commercial plantations and achieving multi-functional utilization of P. lactiflora.