Plant health is closely related to the soil, where microorganisms play a critical and unique role. For instance, Paeonia suffruticosa is an emerging woody oil crop in China with attractive development and utilization prospects. However, black root rot causes wilting of the aboveground plant parts, which significantly affected its seed yield and quality. Studies found that soil microorganisms are critical in maintaining plant health, but how changes in the soil microbial communities affect the healthy and diseased oil peony is unclear. Therefore, our present study used high throughput sequencing and BIOLOG to analyze the rhizosphere soil microbial communities of healthy and diseased oil peonies. Our results revealed that the physical and chemical properties of the soil of the diseased plants had changed, with the ability to metabolize the carbon source being enhanced. Moreover, our research highlighted that the oil peony-infecting fungal pathogenic genus (Fusarium, Cylindrocarpon, and Neocosmospora) was closely associated with oil peony yield reduction and disease aggravation. Further network analysis demonstrated that the bacterial and fungal networks of the diseased plants were more complex than those of the healthy plants. Finally, the inter-kingdom network among the diseased plants further indicated that the lesions destroyed the network and increased the intraspecific correlation between the fungal groups.

High-temperature stress is a key factor that reduces the yields of edible fungi. Auricularia heimuer (A. heimuer) is a nutrient-rich edible fungus that is widely cultivated in China. In this study, we analyzed the physiological, transcriptomic, and metabolomic results of A. heimuer (variety “Hei29”) under high-temperature stress. Our findings revealed that high temperatures (30 °C and 35 °C) significantly reduced hyphal growth, increased malondialdehyde content and antioxidant enzyme activity, and enhanced the accumulation of secondary metabolites, such as phenolic compounds and flavonoids. A total of 15 candidate genes potentially responsive to high-temperature stress were identified through transcriptomic analysis, including those involved in regulating antioxidant defense, heat shock response, sugar metabolism, amino acid metabolism, and accumulating secondary metabolites. Metabolomic analysis identified three candidate metabolites potentially responsive to high-temperature stress, including kinetin, flavonoids, and caffeic acid, as well as several metabolic pathways, including nucleotide metabolism, ABC transporters, and cofactor biosynthesis. These mechanisms help mitigate oxidative damage to cellular structures and energy deficits caused by elevated temperatures, enabling the fungus to maintain cellular stability, metabolic function, and growth under heat stress. This study is the first to explore the molecular mechanism of A. heimuer in response to high-temperature stress. The results provide valuable insights into the molecular mechanisms of heat stress tolerance in A. heimuer, highlighting potential targets for developing heat-tolerant strains for industrial application.

Major latex proteins, or MLPs, are crucial to plants’ capacity to grow, develop, and endure biotic and abiotic stresses. The MLP gene family has been found in numerous plants, but little is known about its role in Populus simonii × P. nigra. This study discovered and assessed 43 PtMLP genes that were unevenly dispersed throughout 12 chromosomes in terms of their physicochemical characteristics, gene structure, conserved motifs, and protein localization. Based on their phylogeny and protein structural characteristics, three separate subclasses of PtMLP family were identified. Segmental and tandem duplication were found to be essential variables in the expansion of the PtMLP genes. The involvement of the PtMLP genes in growth and development, as well as in the responses to different hormones and stresses, was demonstrated by cis-regulatory element prediction. The PtMLP genes showed varying expression patterns in various tissues and under different conditions (cold, salt, and drought stress), as demonstrated in RNA-Seq databases, suggesting that PsnMLP may have different functions. Following the further investigation of the genes demonstrating notable variations in expression before and after the application of three stresses, PsnMLP5 was identified as a candidate gene. Subsequent studies revealed that PsnMLP5 could be induced by ABA treatment. This study paves the way for further investigations into the MLP genes’ functional mechanisms in response to abiotic stressors, as well as the ways in which they can be utilized in poplar breeding for improved stress tolerance.

Heavy metal pollution and soil salinization harm human health and the environment. Phytoremediation is a widely accepted soil decontamination method, with woody plants being particularly effective due to their large biomass and extensive root systems. In this study, we identified and cloned PsnMLP328 from Populus simonii × P. nigra and demonstrated its role in mitigating salt and cadmium stress. PsnMLP328 expression was up-regulated under both stress conditions, and its overexpression in tobacco enhanced resistance to these stresses, albeit through distinct mechanisms. Transgenic plants exhibited increased Cd²⁺ uptake and a higher biomass, alleviating Cd²⁺-induced growth inhibition. Additionally, PsnMLP328 boosted proline content, chlorophyll levels, and antioxidative enzyme activities (POD, SOD) under Cd²⁺ stress, likely by protecting cells from oxidative damage. Expression analysis revealed that PsnMLP328 down-regulated the cadmium transporter Nramp2 while up-regulating YSL2 (another cadmium transporter) and potassium channels (AKT1 and AKT2/3), suggesting its role in modulating K⁺ and Cd²⁺ homeostasis. These findings indicate that PsnMLP328 enhances tobacco resistance to salt and cadmium stress, particularly the latter. This study is the first to elucidate the function of poplar MLP family genes under salt and cadmium stress, advancing our understanding of MLP gene roles in heavy metal stress and offering new insights for remediating salinized and heavy metal-contaminated soils.

Intensifying drought stress under global climate change poses a significant threat to woody plants, highlighting the critical need to identify key genes conferring drought tolerance. Here, we characterized PsnSAUR6, a Small Auxin Upregulated RNA (SAUR) family gene from poplar (Populus simonii × P. nigra) that is responsive to drought and abscisic acid (ABA). Overexpression of PsnSAUR6 in transgenic tobacco conferred superior drought tolerance, evidenced by increased biomass, enhanced root elongation, improved stomatal regulation, and favorable physiological responses, including higher proline content and peroxidase (POD) activity but lower malondialdehyde (MDA). Transcriptome analysis revealed that under water deficit, PsnSAUR6 suppressed the ABA negative regulator PP2C37 while upregulating key antioxidant defense-related transcription factors (ERF020, NAC83, MYB2) and the potassium transporter HAK5. Collectively, these findings establish PsnSAUR6 as a positive regulator in ABA-mediated drought adaptation, presenting it as a promising genetic target for enhancing the climate resilience of woody plants.