Stem strength plays a crucial role in the growth and development of plants, as well as in their flowering and fruiting. It not only impacts the lodging resistance of crops, but also influences the ornamental value of ornamental plants. Stem development is closely linked to stem strength; however, the roles of the SPL transcription factors in the stem development of herbaceous peony (Paeonia lactiflora Pall.) are not yet fully elucidated. In this study, we obtained and cloned the full-length sequence of PlSPL14, encoding 1085 amino acids. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression level of PlSPL14 gradually increased with the stem development of P. lactiflora and was significantly expressed in vascular bundles. Subsequently, utilizing the techniques of virus-induced gene silencing (VIGS) and heterologous overexpression in tobacco (Nicotiana tabacum L.), it was determined that PlSPL14-silenced P. lactiflora had a thinner xylem thickness, a decreased stem diameter, and weakened stem strength, while PlSPL14-overexpressing tobacco resulted in a thicker xylem thickness, an increased stem diameter, and enhanced stem strength. Further screening of the interacting proteins of PlSPL14 using a yeast two-hybrid (Y2H) assay revealed an interactive relationship between PlSPL14 and PlSLR1 protein, which acts as a negative regulator of gibberellin (GA). Additionally, the expression level of PlSLR1 gradually decreased during the stem development of P. lactiflora. The above results suggest that PlSPL14 may play a positive regulatory role in stem development and act in the xylem, making it a potential candidate gene for enhancing stem straightness in plants.

Stems are prone to bending or lodging due to inadequate stem strength, which seriously reduces the cut-flower ornamental quality of herbaceous peony (Paeonia lactiflora Pall.). Plant LACCASE (LAC), a copper-containing polyphenol oxidase, has been shown to participate in the polymerization process of monolignols; however, the role of LAC in regulating the stem strength of P. lactiflora remains unclear. Here, the full-length cDNA of PlLAC15, which demonstrated a positive association with stem strength, was isolated. It consisted of 1790 nucleotides, encoding 565 amino acids that had four typical laccase copper ion-binding domains. Moreover, PlLAC15 was highly expressed in the stem, and its expression level gradually significantly increased during stem development. Furthermore, PlLAC15 was found to be localized specifically to the cell wall, and its recombinant protein exhibited laccase activity. Additionally, the role of PlLAC15 in regulating the stem strength of P. lactiflora was confirmed by transgenic studies. When PlLAC15 was overexpressed in tobacco, stem strength increased by more than 50%, S-lignin was significantly deposited, and the lignification degree of stem xylem fiber cells increased. These results suggested that PlLAC15 facilitated S-lignin deposition to enhance stem strength in P. lactiflora, which would provide precious information that benefits future exploration of stem bending or lodging resistance in plants.

Sorghum is an increasingly popular topic of research in elucidating survival and adaptation approaches to augmented salinity. Nonetheless, little is known about the outcome and modulatory networks involved in the gibberellic acid (GA3)-induced salt stress alleviation in sorghum. Here, we identified 50 mg/L GA3 as the optimal concentration for sorghum ('Jitian 3') development under salt stress. Based on genome-wide DNA methylation analysis, CpG sites displayed the most abundant methylation statuses among all stages, with a mean value of 68.2 %, then CHG (57.9 %), and CHH (21.2 %). We identified 18,032 differentially methylated regions (DMRs) in the GA3-exposed groups. In particular, we recognized 5943 DMR genes and 269 DMR-promoter genes. Using conjoint transcriptome and DNA methylation analyses, we identified 337 important methylated-genes, which were involved in "phenylpropanoid biosynthesis", "arginine and proline metabolism" and "tyrosine metabolism". Together, the aforementioned data provides an in-depth understanding of the epigenetic modulation of gene expression during GA3 treatment.

High-temperature stress severely restricts plant growth and development by inducing oxidative damage and photosynthetic inhibition. Allene oxide synthase (AOS) is a key enzyme in jasmonic acid (JA) biosynthesis, yet its role in the high-temperature stress response of woody ornamental plants remains largely uncharacterized. In this study, PsAOS3 was isolated and characterized from tree peony (Paeonia suffruticosa Andr.), an economically important ornamental species susceptible to high-temperature stress. PsAOS3 was localized to the plasma membrane and was strongly induced by high-temperature stress. Functional analyses using virus induced gene silencing in tree peony showed that silencing of PsAOS3 accelerated chlorophyll loss, increased reactive oxygen species (ROS) accumulation, impaired photosystem II efficiency and membrane integrity, and reduced antioxidant enzymes and endogenous JA contents under high-temperature stress. Conversely, overexpression of PsAOS3 in tobacco (Nicotiana tabacum L.) alleviated chlorophyll loss, decreased ROS accumulation, improved photosystem II efficiency and membrane integrity, and elevated antioxidant enzymes and endogenous JA contents under high-temperature stress. Collectively, this study reveals a potential role of PsAOS3 in regulating high-temperature responses in tree peony.

Stem development determines plant architecture and mechanical support, directly affecting yield, lodging resistance, and ornamental quality. Microtubules are essential components of the plant cytoskeleton, but their role in stem development in herbaceous peony (Paeonia lactiflora Pall.) remains largely unexplored. Here, a β-tubulin gene, PlTUB1, was identified from P. lactiflora. Its coding sequence was 1353 bp in length, encoding a 450-amino-acid protein that localized to microtubules, and its transcript levels declined progressively during stem development. Transient virus-induced gene silencing of PlTUB1 in P. lactiflora, with a silencing efficiency of approximately 55%, enhanced stem development, with increased stem diameter, elevated cellulose accumulation, and thickened secondary walls. Given that cellulose deposition and secondary wall thickening were closely associated with cortical microtubule organization, the role of PlTUB1 in microtubule regulation was further examined. Heterologous overexpression of PlTUB1 in Arabidopsis thaliana disrupted transverse microtubule alignment, reduced cellulose deposition, and impaired secondary wall and xylem development, thereby confirming the mechanistic link between PlTUB1 and microtubule organization. Collectively, these findings demonstrated that PlTUB1 negatively regulates stem development by modulating microtubule organization and secondary wall deposition, providing new insights into the cytoskeletal regulation of stem development in P. lactiflora.

This review focuses on the synergistic roles of plant growth-promoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF) in horticultural systems, highlighting their mechanisms from physiological functions to molecular regulation and community-level synergy. PGPR and PGPF enhance nutrient acquisition, modulate phytohormones, induce systemic resistance, and alleviate abiotic stresses through complementary pathways. At the molecular level, microbial signals trigger downstream signaling cascades, leading to transcriptional reprogramming and epigenetic priming for long-lasting stress memory. The coexistence of PGPR and PGPF can generate synergistic benefits that may outperform single strains under suitable host, microbial, and environmental conditions; however, challenges remain in strain antagonism, host genotype specificity, environmental dependence, formulation instability, and regulatory hurdles. This review provides a conceptual roadmap for precision microbiome management, shifting from empirical application toward predictive, mechanism-guided consortium design. Finally, leveraging advanced technologies (multi-omics, synthetic biology, and AI-driven modeling) together with the synergistic actions of PGPR and PGPF offers directions for achieving sustainable and climate-resilient horticulture.