Increased atmospheric nitrogen (N) deposition and soil salinization commonly co-occur in subtropical economic forests, and responses to these stressors differ between sexes in dioecious plants. In this study, we explored soil chemical and stoichiometric responses of male and female Torreya grandis to N deposition under salt stress by adopting a two-factor completely randomized design. The two factors were (1) plant sex (2-year-old grafted male and female seedlings of T. grandis) and (2) environmental treatment (four nitrogen deposition levels: low, moderate, and high N combined with salt stress, as well as a control without salt addition). We then determined the rhizosphere C, N, P, Ca, K, and Mg concentrations and their stoichiometric ratios. The results showed that all indicators were significantly affected by sex, nitrogen treatment and their interaction (p < 0.0001). Males maintained significantly higher soil C and N levels than females across all treatments, with female soil N and C contents being 5.74–25.72% and 10.78–23.64% lower than those of males, respectively, and exhibiting far more stable stoichiometry. Moderate nitrogen deposition (SMN) increased male C:N, C:P and N:P ratios by 38.76%, 59.75% and 13.84%, distinctly lower than the 85.89%, 98.20% and 16.04% increments in females. In contrast, females had higher Mg content under all salt–nitrogen-combined treatments and greater stoichiometric plasticity, showing a 37.55% higher C:N ratio than males under low nitrogen addition (SLN). Moderate N relieved salt-induced nutrient limitation and alleviated salt-induced P immobilization, while excessive N (SHN) exacerbated stoichiometric imbalance: SHN elevated the N:P ratio by 109.73% in males and only 69.59% in females, narrowing the sexual difference in C:N ratio to 10.92% and triggering severe phosphorus limitation in male rhizosphere soil. Soil–leaf nutrient relationships and correlations differed greatly between sexes, indicating divergent nutrient adaptation strategies. Males adopted a Ca-dominated stress tolerance strategy, and females depended on Mg homeostasis for reproduction. This work provides a scientific basis for sex-specific nutrient regulation and sustainable cultivation of T. grandis under global change.

Abstract With the expansion of modern horticultural production systems, anthocyanins have attracted increasing attention for their dual role in imparting vibrant coloration and delivering health-promoting benefits. Preharvest temperature management, particularly controlled low-temperature exposure, has emerged as an effective strategy to enhance anthocyanin accumulation in horticultural crops. Despite extensive molecular insights, decision-driven temperature management (DDTM) frameworks that integrate species-, genotype-, and operational parameter-specific strategies for plant factory applications remain lacking. This review addresses this gap by proposing a DDTM-based framework that links molecular regulation to operational protocols for precise anthocyanin enrichment. Evidence is synthesized across diverse horticultural crops representing major production families, including Brassicaceae, Solanaceae, Rosaceae, and other representative horticultural groups, selected for their economic importance, high anthocyanin potential, and relevance to human health. Species- and genotype-dependent responses are highlighted, and key operational parameters, including temperature range, exposure duration, and preharvest timing, are analyzed to balance pigmentation intensity, biomass production, and energy efficiency. Plant factories are emphasized as enabling platforms for short-term end-of-cycle cooling and diurnal temperature modulation, which can be integrated with light spectrum management to optimize anthocyanin accumulation while maintaining yield stability. By organizing current knowledge into practical, decision-oriented temperature strategies, this review provides a framework to improve nutritional quality, compositional consistency, and functional value of anthocyanin-rich crops, supporting horticulture-driven quality assurance and resilient controlled-environment production systems.

Rhododendron species are valued for their ecological, horticultural, and cultural importance and are increasingly threatened by climate-related stresses, including drought, frost, extreme heat, and nutrient imbalance. Over the past decade, physiological, biochemical, and nutrient-based studies, combined with the rapid expansion of transcriptomic, proteomic, metabolomic, and emerging epigenomic datasets, have provided new insights into stress-responsive pathways in this genus. However, these findings remain unevenly distributed across species and stress types and are rarely integrated across biological scales or linked directly to whole-plant performance. This review critically synthesizes recent advances in nutrient dynamics, mycorrhizal associations, hormonal regulation, and omics-based molecular responses underlying climate stress adaptation in Rhododendron. By integrating physiological traits with multi-omics evidence, we identify conserved regulatory modules, key metabolic and redox pathways, and trade-offs between growth and stress tolerance. We further highlight major genomic and experimental limitations, including taxonomic bias, short-term experimental designs, incomplete genome resources, and limited functional validation of candidate genes. Finally, future research priorities are proposed that emphasize integrative multi-omics approaches, genome-enabled functional studies, and systems-level modelling to advance climate-resilient Rhododendron conservation and breeding strategies. This synthesis provides a framework for translating molecular insights into horticultural and ecological applications under ongoing climate change.

Revealing the interactions between stand structure factors and ecosystem functions is crucial for enhancing forest soil and water conservation, as well as carbon storage. However, the optimal stand structure configuration for achieving superior ecological functions remains unclear, particularly in complex subtropical evergreen broad-leaved forests. Using Schima superba Gardn. et Champ. forests in Dongbai Mountain as a case study, this study investigated the effects of seven stand structure factors—stand density, canopy density, uniform angle index, and mixing degree—on three key ecosystem functions, water-holding function, soil improvement function, and carbon sequestration. Redundancy analysis (RDA) and structural equation modeling (SEM) were employed to quantify these relationships. The results identified stand density as the most influential factor, directly or indirectly affecting ecosystem functions by regulating other structural attributes. Optimal structural configurations were determined, including stand densities of 1228, 1532, and 1675 plants·hm−2 for maximizing water-holding function, soil improvement function, and carbon sequestration, respectively. Recommendations emphasize adjusting stand density, canopy density, uniform angle index, and mixing degree according to site-specific conditions. Practical strategies, such as replanting, intercropping, and introducing functionally complementary species, should aim to enrich vertical structure, maintain species randomness, and avoid dominance by a single species or excessive density. These findings offer actionable insights for improving the ecological functions of subtropical forests and have broader implications for sustainable forestry management, advancing regional carbon neutrality, and addressing global ecological challenges.

Rhododendrons naturally inhabit acidic soils where aluminum (Al) toxicity severely restricts plant growth, yet the molecular basis underlying cultivar-dependent differences in Al tolerance remains poorly understood. In this study, we compared the transcriptional and physiological responses of an Al-resistant cultivar (Kangnaixin) and an Al-sensitive cultivar (Baijinpao) under Al stress. Transcriptome analysis was performed to identify Al-responsive differentially expressed genes (DEGs), followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to elucidate functional categories and metabolic pathways involved in stress adaptation. In addition, the Al tolerance-related gene RsALS3 was cloned and functionally characterized through heterologous overexpression in Arabidopsis thaliana. The two cultivars exhibited distinct transcriptional profiles in response to Al stress, with DEGs significantly enriched in abiotic stress responses, membrane-associated functions, and key metabolic pathways, including starch and sucrose metabolism, phenylpropanoid and flavonoid biosynthesis, and photosynthesis-related processes. These results suggest that Al stress disrupts membrane integrity and alters carbon metabolism in Rhododendron. Functional validation demonstrated that RsALS3 overexpression moderately alleviated Al-induced toxicity in A. thaliana, as evidenced by reduced leaf damage and improved photosynthetic efficiency. Although the observed phenotypic differences were modest, and some chlorophyll fluorescence kinetics data did not reach strong statistical significance. The overall physiological trends support a potential role of RsALS3 in Al stress adaptation. Collectively, these findings provide insight into cultivar-specific Al stress responses in Rhododendron and identify RsALS3 as a promising candidate gene for further investigation aimed at improving adaptation to acidic soils.

Cunninghamia lanceolata, contributing 25% to China’s commercial timber production, faces severe drought threats. However, provenance-specific photosynthetic adaptations remain poorly understood. Here, we compared gas exchange, prompt/delayed fluorescence (PF/DF), and modulated 820-nm reflection (MR) responses of two provenances (JXJJ and FJSM) under different drought treatment times. JXJJ maintained a higher net photosynthetic rate (Pn) and stomatal conductance (Gs) than FJSM under drought stress. The declining rates of FV/FM, φEO, ΨO, δRO, PIABS, TRO/CSM, and ETO/CSM were much more rapid in the FJSM than in the JXJJ. An MR kinetics analysis revealed significantly greater PSI impairment in FJSM, evidenced by a 60.2% reduction in P700+ re-reduction rate (Vred) compared to only 44.4% in JXJJ (p < 0.05) at 20 d drought treatment. Similarly, DF measurements demonstrated more pronounced PSII energy transfer disruption in FJSM, with the I2/I1 ratio increasing by 51.3% vs. 43.0% in JXJJ at 20 d drought treatment. These results demonstrate JXJJ’s superior drought resilience through coordinated stomatal and non-stomatal regulation. Our findings provide actionable criteria for selecting drought-tolerant C. lanceolata provenances, which is essential for sustainable forestry as the climate changes. This study underscores the significance of photosynthetic activity in how C. lanceolata responds to drought and gives insights into boosting drought tolerance in forest species through genetic improvements.

Numerous studies on biodiversity–ecosystem functioning (BEF) have shown that mixed plantations can improve the ecological benefits of forest ecosystems. However, few studies have employed a multi-dimensional approach to study the integrated ecological benefits of mixed plantations. This study aims to evaluate the stand characteristics and ecological benefits of different forest types by examining various ecological indicators, including trees, shrubs, herbs, and soil properties. Focusing on typical mixed broadleaf–conifer plantations (MBCPs), mixed coniferous plantations (MCPs), and pure Cunninghamia lanceolata (Lamb.) Hook plantations (PCLs) at the Guiyang Plantation Farm, Suichang, we analyzed growth performance, spatial structure, understory vegetation diversity, and soil physicochemical properties across these forest types. For each forest type, one 100 × 100 m plot was established. Within each plot, five 20 × 20 m subplots were selected for investigation. Our results show that the aboveground biomass of MCPs is higher than that of MBCPs and PCLs, with increases of 46.58% and 177.29%, respectively. Furthermore, both mixed plantations offer better stand structure compared to pure plantations. In mixed plantations, the MBCPs exhibited a high degree of niche overlap, indicating that interspecific competition outweighed complementarity, whereas the MCPs demonstrated a more favorable stand structure. MCPs also exhibit significantly greater understory vegetation diversity compared to MBCPs and PCLs, with increases of 4.19%–13.04% and 10.34%–36.99%, respectively. Additionally, mixed plantations enhance soil moisture retention and fertility. With the onset of global warming and the increasing prevalence of extreme weather events, the establishment of artificial mixed plantations is an essential strategy to address climate change and enhance the ecological benefits of plantations.

Global climate change poses a great obstacle to the sustainability of world forestry, and the trifecta of enhancing forest stock, minimizing greenhouse gas emissions, and attaining sustainable forest management is still challenging. Climate-smart forestry (CSF), however, offers promising solutions to these issues, with its core objective being to foster sustainable development through enhanced forest resilience, reduced greenhouse gas emissions, and boosted forest productivity and income. This emerging focus on CSF seeks to understand the mechanisms of interactions between forest ecosystems and climate change and eventually find locally acceptable solutions. This review delves into the developmental objectives of CSF, providing a new insight into the latest research advances and practical experience in CSF among eight Europe and American countries, including Brazil, USA, Czech, Finland, etc. Meanwhile, we identify the main challenges that CSF is facing currently, including the climate change uncertainty, disconnection among policy, science, and practice, and trade-offs between different CSF objectives. To address these challenges, we proposed five potential aspects for CSF development and sketched their main applications. Specifically, Technological innovation and digital applications are highly encouraged, including GIS and remote sensing, Internet of Things (IoT), and artificial intelligence technologies. Besides, Intelligent logging operations and wood processing, forest bioeconomy should also be considered to promote the CSF development. The results offer new perspectives and strategies for mitigating climate change via sustainable forestry management and protecting forest economies and communities in the context of accelerated global climate change.

Rhododendron simsii (R. simsii), a significant ornamental plant species, is adversely affected by the severe soil heavy metal pollution resulting from rapid industrialization, particularly in terms of its growth environment. Cadmium (Cd), a representative heavy metal pollutant, poses a significant threat to plant growth and photosynthetic physiology. Despite the importance of understanding Cd stress resistance in rhododendrons, research in this area is limited. This study focused on the role of exogenous melatonin (MT) in mitigating Cd-induced stress, emphasizing its impact on photosynthetic physiology. Gas exchange parameters, prompt and delayed fluorescence (DF), 820 nm modulated reflectance (Mr820), and antioxidant enzyme activity, were measured. The findings revealed that under Cd stress, MT-free treatment imposed a more severe limitation on both stomatal and non-stomatal processes in R. simsii leaves, significantly reducing the net photosynthetic rate. In contrast, exogenous MT improved photosynthetic efficiency by increasing the maximum photochemical efficiency of photosystem II, the quantum yield of electron transport, and the photosynthetic performance index. DF and Mr820 analysis demonstrated that MT provided robust protection to both the donor and receptor sides of photosystems I and II. Furthermore, MT significantly decreased malondialdehyde (MDA) content, a marker of oxidative stress, and enhanced the activity of antioxidant enzymes, including superoxide dismutase (SOD) and guaiacol peroxidase (POD). In conclusion, exogenous MT plays a critical role in alleviating Cd-induced stress by enhancing antioxidant defense mechanisms and safeguarding the photosynthetic apparatus, thereby improving the Cd tolerance of R. simsii.

In subtropical regions of China, the expansion of Moso bamboo has become increasingly prominent, resulting in massive mortality of original trees in adjacent forest stands. Significant changes have also occurred in the population characteristics and spatial distribution patterns of these native tree species. This study aims to examine the impacts of Moso bamboo (Phyllostachys edulis) expansion on the successional dynamics of coniferous and broad-leaved mixed forests. Three sample plots were successively set up in the transition zone from bamboo to conifer and broad-leaved forest, including conifer and broad-leaved mixed forest (CF), transition forest (TF), and Moso bamboo forest (MF); a total of 72 10 m × 10 m quadrats (24 per forest type) were included. The species composition, diameter class structure and distribution pattern of living stems and snags (dead standing stems) were studied. The results showed that during the late expansion phase of bamboo, the density of living stems and snags separately increased by 2234 stems·ha−1 and 433 stems·ha−1, basal area increments of 23.45 m2·ha−1 and 7.81 m2·ha−1. The individuals with large diameter in living stems and snags gradually decreased, and the distribution range of the diameter steps mainly narrowed to 10–15 cm. On the scale of 0–10 m, the spatial pattern of standing stems changed from random and weak aggregation distribution to strong aggregation distribution and then to weak aggregation and random distribution in the three stands, while the overall distribution of snags in the three stands was random. The spatial correlation between living stems and snags evolved from uncorrelated in CF, to significant positive correlation in TF, and then to positive correlation and uncorrelation in MF. These results indicated that the bamboo expansion accelerated the mortality rate of the original tree species, leading to the diversity of tree species decreased, the composition of diameter classes was simplified, the degree of stem aggregation increased, and intra- and inter-species competition became the main reasons for tree death.

Volatile terpenoids (VTs) are key secondary metabolites that play dual roles as endogenous antioxidants and airborne signals in plants under abiotic stress. Their biosynthesis is orchestrated via the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, with metabolic plasticity regulated by transcription factors, phytohormonal crosstalk, and stress-responsive elements. Recent advances have revealed that VTs such as isoprene, monoterpenes, and sesquiterpenes help mitigate oxidative stress by scavenging reactive oxygen species (ROS) and modulating antioxidant enzyme systems. However, regulatory mechanisms of stress-induced VT emissions remain fragmented and species-dependent. This review synthesizes current knowledge of VT biosynthesis and emission under abiotic stress, highlights their antioxidant functions and regulatory architecture, and underscores their protective roles in redox homeostasis and stress signal transduction. By identifying key metabolic nodes (e.g., TPS, DXS and MYC2) and stress-responsive pathways, we propose potential molecular targets for the development of stress-resilient cultivars. The integration of VT-based traits into breeding strategies and production-oriented metabolic engineering offers promising avenues for improving crop performance, reducing oxidative damage, and supporting sustainable agricultural systems.

Rhododendron simsii Planch. are one of the top ten traditional famous flowers in China, with high ornamental value. In order to explore the affinity of different combinations and screen out high-quality parents and pollination combinations, Rhododendron hainanense Merr., Rhododendron simsii 'xianhe', Rhododendron x pulchrum Sweet and Rhododendron indicum (L.) Sweet were used as materials. The pollen viability, stigma receptivity, pollen germination and pollen tube development characteristics were determined, and the difference of pollen tube growth among different pollination combinations were analyzed. The results showed that the pollen vitality of R. hainanense, R. simsii 'xianhe' and R. pulchrum was above 80%, which could be used as high quality male parents. Based on the optimal pollination time, R. hainanense and R. pulchrum can be determined as high-quality female parents. The germination rates of pollen in all combinations showed a slow upward trend. After 8 days of pollination, the pollen tubes in all combinations had reached the ovary position. However, Interspecific cross-pollination exhibited significant advantages over intraspecific self-pollination in both pollen germination rate and speed. The results of this study can provide reliable theoretical basis for hybrid breeding of Rhododendron and screening of high-quality parents.

Elevated CO2 levels and increased temperatures are two driving forces of climate change. Plants, including economic forest tree species, will confront the challenge of the combined effects of these two environmental factors under future climate conditions. This study focused on analyzing the influence of CO2 (ambient 400 mu mol mol-1; elevated 800 mu mol mol-1) and atmospheric temperature (current 25 degrees C; future warming 29 degrees C) treatments on the photosynthetic characteristics and non-structural carbohydrates of precious subtropical nut tree species Torreya grandis seedlings. The findings suggested that Torreya exhibited greater sensitivity to elevated CO2 than to warming. Elevated CO2 boosted the seedlings' maximum carboxylation rate of Rubisco (from 48.3 to 67.9 mu mol m-2 s-1) and photosynthetic rate (from 5.1 to 13.3 mu mol m-2 s-1), while reducing leaf nitrogen concentration. The increased activities of carbonic anhydrase and phosphoenolpyruvate carboxylase under elevated CO2 might reconcile the contradiction between low leaf nitrogen levels and high photosynthetic capacity. The accumulation of starch and soluble sugars, primarily starch, led to a significant increase in non-structural carbohydrates in Torreya. Elevated COQ increased the starch content in Torreya leaves by approximately fourfold and the activity of ADP-glucose pyrophosphorylase by roughly threefold. This suggested that Torreya appeared to utilize starch as a carbon sink for storing photosynthates, while maintaining a lower soluble sugar/starch ratio to prevent the inhibition of photosynthesis by the accumulation of photosynthates. In summary, under elevated CO2 and increased temperature, Torreya seedlings fixed more CO2 by enhancing photosynthesis and carbon metabolism. Our findings suggested that Torreya might benefit under future climate conditions.

Basic helix–loop–helix (bHLH) transcription factors play significant roles in plant growth and organ development and diverse biochemical processes. However, the function of bHLH transcription factors in woody plants is not fully understood. In this study, the bHLH gene family in Rhododendron × pulchrum Sweet was identified and characterized using whole-genome data. A total of 109 bHLH family genes (RpbHLHs) were identified in R. pulchrum, and their expression levels were analyzed in flowers of different colors and developmental stages. The results showed that the RpbHLH family is divided into 24 subfamilies. Chromosomal localization and collinearity analyses revealed numerous duplication events during evolution, which is one of the main reasons for the diversification of gene functions. The bHLH domains showed relative conservation of RpbHLH proteins. In the promoter regions of the RpbHLHs, various cis-regulatory elements involved in light response, gibberellic acid (GA) response, and abscisic acid (ABA) response were identified. These elements may regulate flower development and pigment synthesis. A Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis of the target RpbHLHs revealed that 25 genes are enriched in the flavonoid biosynthetic pathway. Potential RpbHLHs related to flower development and pigment synthesis were identified through a transcriptome analysis and validated through quantitative reverse transcription PCR (qRT-PCR). This study will enhance our understanding of RpbHLH functions and provide a reference for the study of flower development and coloration in R. pulchrum.

IntroductionThe intrinsic relationships among plants, litter, and soil nutrient characteristics, along with the responses of ecological stoichiometry to nutrient utilization, are critical for understanding the mechanisms of nutrient cycling. However, limited research in this area has constrained our comprehension of nutrient dynamics within ecosystems.MethodsTo investigate the stoichiometric characteristics and nutrient resorption traits of Torreya grandis plantations across various stand ages, as well as their adaptive strategies and nutrient utilization mechanisms under local growth conditions, we conducted a study in the T. grandis Forest Park. This study examined five stand age groups: young (20 years), near-mature (50 years), mature (80 years), over-mature (100 years), and thousand (1,000 years). We measured the nutrient contents of soil, fresh leaves, and litterfall, and analyzed their stoichiometric relationships and nutrient resorption characteristics.Results1.The growth of T. grandis plantations was primarily limited by nitrogen (N) during the early stages, transitioning to phosphorus (P) limitation with increasing stand age, particularly in the over-mature stage. High C:N and C:P ratios in leaves indicated low N and P use efficiency. 2.Leaf nutrient concentrations remained relatively stable across different stand ages, whereas nutrient concentrations in litterfall gradually declined, indicating an increase in nutrient cycling efficiency. Meanwhile, soil nutrient accumulation showed a gradual increase with stand development. T. grandis exhibited distinct nutrient resorption strategies at different stand ages: phosphorus resorption efficiency (PRE) was higher in young stands, whereas nitrogen resorption efficiency (NRE) significantly increased in mature and over-mature stands. Furthermore, this nutrient allocation mechanism influenced the nutritional content of T. grandis seeds, highlighting the significant impact of stand age on seed quality. 3.The nutrient characteristics of T. grandis plantations are influenced by both stand age and soil nutrient availability.Management practices should prioritize the supplementation of soil nutrients, particularly P, and the enhancement of nutrient cycling efficiency.DiscussionThis study offers a scientific foundation for the sustainable management and production of T. grandis plantations in the region, highlighting the importance of targeted soil nutrient management to improve ecosystem productivity and sustainability.

Rhododendron L., a renowned ornamental species and one of the ten famous flowers in China, is highly regarded for its aesthetic value and extensive applications in landscaping. However, its growth and quality are significantly compromised by drought stress, particularly in regions with dry conditions. To elucidate the drought response mechanisms of Rhododendron, two cultivars, ‘SaKeSiZhiXing’ (SKSZX) and ‘TuRuiMeiGui’ (TRMG), were subjected to natural drought stress, and changes in chlorophyll fluorescence and transcriptomic profiles were examined at 0 days (d), 4 d, and 8 d of drought exposure. An OJIP fluorescence transient (O-J-I-P) analysis revealed a progressive decline in the FP parameter and an increase in the FJ parameter as drought stress intensified. Additionally, a delayed fluorescence (DF) analysis showed a gradual reduction in the I1 and I2 values within the induction and decay curves under prolonged drought conditions. The 820 nm curve indicated the deactivation of a transient phase characterized by a rapid decline, followed by a slow recovery in the modulated reflection (MR) signal. A transcriptomic analysis of leaves identified 24,352, 18,688, and 32,261 differentially expressed genes (DEGs) in SKSZX at 0 d, 4 d, and 8 d of drought treatment, respectively. In contrast, TRMG exhibited more pronounced and earlier drought-induced alterations. These DEGs were primarily enriched in pathways related to phenylpropanoid biosynthesis, plant hormone signaling, photosynthesis, and photosynthesis-antenna proteins. Additionally, 565 transcription factors (TFs) were identified, including bHLH, WRKY, bZIP, MYB-related, MYB, C2H2, and HSF families. The drought-induced changes in TRMG were more substantial and occurred earlier compared to SKSZX, with a greater impairment in the electron transfer capacity at both the donor and acceptor sides of photosystem II (PSII). This study provides valuable insights into the molecular mechanisms underlying drought tolerance in Rhododendron and offers a foundation for molecular breeding strategies aimed at enhancing drought resistance in future cultivars.

Abiotic stresses are considered as a significant factor restricting horticultural crop productivity and quality. Drought stress is a major environmental constraint among the emerging concerns. Plants have significant susceptibility to drought stress, resulting in a marked decline in production during the last several decades. The development of effective strategies to mitigate drought stress is essential for sustainable agriculture and food security, especially considering the continuous growth of the world population. Several studies suggested that exogenous application of phytohormone to plants can improve drought stress tolerance by activating molecular and physiological defense systems. Phytohormone pretreatment is considered a potential approach for alleviating drought stress in horticultural plants. In addition, melatonin, salicylic acid, jasmonates, strigolactones, brassinosteroids, and gamma-aminobutyric acid are essential phytohormones that function as growth regulators and mitigate the effects of drought stress. These hormones frequently interact with one another to improve the survival of plants in drought-stressed environments. To sum up, this review will predominantly elucidate the role of phytohormones and related mechanisms in drought tolerance across various horticulture crop species.

The effects of simulated acid rain (SAR) on the photosynthetic performance of subtropical coniferous species have not been thoroughly investigated. In this study, we treated two coniferous species, Pinus massoniana (PM) and Cunninghamia lanceolata (CL), with four gradients of SAR and then analyzed their photosynthetic activities through measurements of gas exchange, prompt fluorescence (PF), delayed fluorescence (DF), and modulated reflection at 820 nm (MR820). Gas exchange analysis indicated that the decrease in the net photosynthetic rate (Pn) in PM and CL was unrelated to stomatal factors. For the PF transients, SAR induced positive K-band and L-band, a significant reduction in photosynthetic performance index (PIABS), the quantum yield of electron transfer per unit cross-section (ETO/CSm), and maximal photochemical efficiency of photosystem II (Fv/Fm). Analysis of the MR820 kinetics showed that the re-reduction kinetics of PSI reaction center (P700+) and plastocyanin (PC+) became slower and occurred at later times under SAR treatment. For the DF signals, a decrease in the amplitude of the DF induction curve reduced the maximum value of DF (I1). These results suggested that SAR obstructed photosystem II (PSII) donor-side and acceptor-side electron transfer capacity, impaired the connectivity between PSII and PSI, and destroyed the oxygen-evolving complex (OEC). However, PM was better able to withstand SAR stress than CL, likely because of the activation of a protective mechanism.

Rhododendron is the largest genus in Ericaceae and is well known for its diversity and beauty of flowers present in different species,making it a much-revered lineage of ornamental plants.Many species of Rhododendron are intolerant of high temperatures,which are becoming more common and intense in urban areas under global climate change.Therefore,the discovery and description of genes from heat-tolerant Rhododendron lineages are essential in the development of new climate-resilient cultivars.One such species known to be heat tolerant is Rhododendron × pulchrum Sweet.To better understand the genomics of heat tolerance in this species,we assembled a haplotype-resolved and chromosome-scale genome for R.× pulchrum,which had a genome size of 509 Mb;a scaffold N50 of 37 251 370 bp;and contained 35 610 genes.In addition,based on the same reannotation pipeline,we conducted pan-genomic analyses for all seven available chromosome-scale Rhododendron genomes and found 14415 gene groups shared across all species and 18018 gene groups distributed in the other species,including 1879 gene groups found in only a single species.Finally,we analyzed the transcriptomic data from heat-treated and non-heat-treated R.× pulchrum plants to quantify the genes that are most important during heat stress in an effort to inform the development of climate-resilient cultivars.This study provides insight into the genome diversity in Rhododendron and targets several genes related to agronomic traits that may help in further analysis.

Grafting as a crucial horticultural technique has been widely used in the cultivation of Carya cathayensis (Chinese hickory), which is a unique and important economic tree in the northeast of Zhejiang Province and the south of Anhui Province. However, the existing literature lacks research on the potential impact of various rootstocks on the thermal tolerance of Chinese hickory. The objectives of this study were to evaluate heat tolerance in four distinct groups of Chinese hickory, including C. cathayensis grafted onto Carya hunanensis and Carya illinoinensis, one self-grafted group (C. cathayensis grafted onto C. cathayensis), and one non-grafted group (C. cathayensis). We examined photosynthesis parameters, phytohormones, and differentially expressed genes in the four various hickory groups subjected to 25 °C, 35 °C, and 40 °C heat stress (HS). The results demonstrated that grafting onto C. hunanensis and C. illinoinensis exhibited a higher net photosynthetic rate and stomatal conductance, lower intercellular CO2 concentration, and smaller changes in plant hormone content compared to self-grafted and non-grafted group under HS. The transcriptome results revealed that the majority of differentially expressed genes (DEGs) associated with photosynthetic pathways exhibited downregulation under HS, while the degree of variation in grafted groups using C. hunanensis and C. illinoinensis as rootstocks was comparatively lower than that observed in self-grafted and non-grafted groups. The alteration in the expression patterns of DEGs involved in plant hormone synthesis and metabolism under HS corresponded to changes in plant hormone contents. Overall, Chinese hickory grafted onto C. hunanensis and C. illinoinensis exhibited enhanced resistance to high-temperature stress at the juvenile stage.