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Grass‐planting measure is a crucial vegetation approach to mitigate understory soil erosion and improve ecological environment in the red soil region of southern China. This study aimed to quantify the effects of grass (Paspalum wettsteinii Hackel.)‐planting measures on runoff and sediment reduction on slopes of Masson pine plantations under rainstorm conditions. We conducted a rainfall simulation experiment at a rainfall intensity of 2.0 mm/min, comparing single strip (MT1, strip spacing: 145 cm), double strips (MT2, strip spacing: 70 cm), and triple strips (MT3, strip spacing: 45 cm) grass‐planting measures on slope surface runoff generation and soil erosion processes of the young Masson pine (MT0, no grass strip) plantation, and the bare slope (CK) was selected as the control. Results revealed that grass‐planting measures significantly decreased slope erosion parameters compared to CK and MT0. As the average grass coverage increased (MT1 from 10% to 25%, MT2 from 7.5% to 22.5%, MT3 from 7.3% to 25%), the slope surface erosion parameters under the grass‐planting measures decreased, resulting in significantly improved runoff and sediment reduction benefits. The runoff reduction effect could reach 32%, while the sediment reduction effect could reach 88%. Moreover, MT3 demonstrated superior performance over MT2 and MT1, with minimal runoff and sediment reduction effects observed for the MT0. Overall, this study suggests that grass‐planting measures, coupled with the increasing of grass coverage rates, significantly improve runoff and sediment reduction benefits on slopes in regions experiencing heavy rainfall. Among the tested configurations, MT3 emerged as most effective measure for controlling understory soil erosion in Masson pine plantations, especially when its average grass coverage rate reached 25%. These findings provide valuable insights for selecting appropriate grass‐planting strategies, as well as for understanding the underlying mechanisms of how these measures mitigate soil erosion. This scientific reference will aid in the design and implementation of soil and water conservation measures in the region. [ABSTRACT FROM AUTHOR]

Pine wilt disease, caused by Bursaphelenchus xylophilus, is a highly destructive and contagious forest affliction. Often termed the "cancer" of pine trees, it severely impacts the growth of Masson pine (Pinus massoniana). Previous studies have demonstrated that ectopic expression of the PmACRE1 gene from P. massoniana in Arabidopsis thaliana notably enhances resistance to pine wilt nematode infection. To further elucidate the transcriptional regulation and protein interactions of the PmACRE1 in P. massoniana in response to pine wilt nematode infection, we cloned a 1984 bp promoter fragment of the PmACRE1 gene, a transient expression vector was constructed by fusing this promoter with the reporter GFP gene, which successfully activated the GFP expression. DNA pull-down assays identified PmMYB8 as a trans-acting factor regulating PmACRE1 gene expression. Subsequently, we found that the PmACRE1 protein interacts with several proteins, including the ATP synthase CF1 α subunit, ATP synthase CF1 β subunit, extracellular calcium-sensing receptor (PmCAS), caffeoyl-CoA 3-O-methyltransferase (PmCCoAOMT), glutathione peroxidase, NAD+-dependent glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase 1, cinnamyl alcohol dehydrogenase, auxin response factor 16, and dehydrin 1 protein. Bimolecular fluorescence complementation (BiFC) assays confirmed the interactions between PmACRE1 and PmCCoAOMT, as well as PmCAS proteins in vitro. These findings provide preliminary insights into the regulatory role of PmACRE1 in P. massoniana's defense against pine wilt nematode infection. [ABSTRACT FROM AUTHOR]

The masson pine (Pinus massoniana, a coniferous tree species in the pine genus of the Pinaceae family) is the largest organic carbon reservoir in southeastern China, playing an important role in regulating CO2 and maintaining the carbon-oxygen balance of the biosphere. Based on turbulence flux observation data, this study analyzed the characteristics of carbon source and sink changes and influencing factors of the masson pine in Wuyishan National Park during the growing season of 2019 from the ecosystem scale, and estimated the photosynthetic parameters under different conditions. The results showed that the net ecosystem carbon exchange (NEE) of the masson pine during the growing season was -593.06 g CO2 /m². On the daily scale, the diurnal variation of NEE of masson pine was U-shaped, and the carbon sink capacity was strongest from 12 to 14 o'clock. On a monthly scale, carbon sequestration capacity of masson pine was strongest in September (-94.55 g CO2/m²) and relatively weak from May to July. Photosynthetically active radiation was the dominant factor of NEE at night, and there was a significant negative correlation between them. Soil temperature was the dominant factor of NEE at night, and the relationship between them showed a significant quadratic function. The light response curve shows that the maximum photosynthetic rate (Pmax) of the masson pine ecosystem in March and July was higher, while the initial photosynthetic efficiency (α) of vegetation in May was higher. Both Pmax and α were larger when the vapor pressure deficit was between 1~2.5 kPa, which was the most suitable for the masson pine to absorb carbon. The increase of soil water content would lead to the increase of ecosystem respiration (Rd), α and Pmax. When soil water content was supersucated, the increment of Rd was similar to that of Pmax, and the net carbon sequestration of vegetation was no longer increasing. These results were helpful to improve the overall understanding of the carbon sink function of masson pine ecosystem. [ABSTRACT FROM AUTHOR]

The accumulation of phytolith-occluded organic carbon (PhytOC) in soils is great significance for carbon sink of terrestrial ecosystems. To clarify the accumulation law of soil PhytOC in Masson pine forests and to elucidate whether forest management significantly influences the accumulation of PhytOC in soils, soil PhytOC accumulation of the typical Masson pine forests in Southwest China karst area were studied. We tested the hypothesis that forest age obviously affects soil PhytOC accumulation in Masson pine forests and mature Masson pine forests have higher soil PhytOC accumulation than young Masson pine forests. The followed results and conclusions were obtained: (1) Soil phytolith and PhytOC content range of 0–30 cm soil profile in the karst Masson pine forests was 9.67–12.81 g·kg− 1 and 0.17–0.25 g·kg− 1, respectively. (2) Forest stand condition significantly influenced soil PhytOC accumulation in the Masson pine forests. With increasing stand age, soil PhytOC accumulation rose remarkably in the Masson pine forests. (3) Soil physical and chemical properties largely influenced the soil PhytOC accumulation. The calcium-rich, high Si and alkalescent soils in Southwest China karst area were propitious to the preservation and accumulation of PhytOC. (4) There were huge potential of soil phytolith carbon sequestration of Masson pine forests in Southwest China. Forest management measures changing stand density or canopy density is of great significance in increasing soil phytolith carbon sink of Masson pine forests and should be paid more attention for increasing carbon sink of terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

N6-methyladenosine (m6A) RNA modification is the most prevalent form of RNA methylation and plays a crucial role in plant development. However, our understanding of m6A modification in Masson pine (Pinus massoniana Lamb.) remains limited. In this study, a complete analysis of m6A writers, erasers, and readers in Masson pine was performed, and 22 m6A regulatory genes were identified in total, including 7 m6A writers, 7 m6A erases, and 8 readers. Phylogenetic analysis revealed that all m6A regulators involved in Masson pine could be classified into three distinct groups based on their domains and motifs. The tissue expression analysis revealed that the m6A regulatory gene may exert a significant influence on the development of reproductive organs and leaves in Masson pine. Moreover, the results from stress and hormone expression analysis indicated that the m6A regulatory gene in Masson pine might be involved in drought stress response, ABA-signaling-pathway activation, as well as resistance to Monochamus alternatus. This study provided valuable and anticipated insights into the regulatory genes of m6A modification and their potential epigenetic regulatory mechanisms in Masson pine. [ABSTRACT FROM AUTHOR]

The assessment of ecological functions, such as those of forest structure zoning and carbon sinks, heavily relies on forest age classification. Therefore, monitoring forest age is a crucial element of forest resource surveys. With the increased availability of high-quality open-access satellite data and advancements in Unmanned Aerial Vehicle Light Detection and Ranging (UAV-LiDAR) technology, remote sensing has emerged as an essential method for acquiring accurate forest age information. In this study, Sentinel-2 remote sensing data, UAV-LiDAR data, and combined Sentinel-2 and LiDAR data are used as data sources. Three machine learning algorithms, Adaptive Boosting (AdaBoost), Random Forest (RF), and Extreme Random Tree (ERT), are used to predict forest age in a Masson pine (Pinus massoniana Lamb.) forest. The optimal model is used to predict the forest age and simulate the spatial age distribution. The machine learning models based on separate Sentinel-2 and LiDAR data accurately predict the age of the Masson pine forest. Nevertheless, the accuracy of the RF model with combined data was higher than that in other cases, with an accuracy R value of 0.81. The model displayed good stability, and the spatial uncertainty of age estimation was low. Compared with the RF model using only Sentinel-2 data (R = 0.43), the RF model with combined LiDAR and Sentinel-2 data achieved the highest accuracy, with R values 88.37% higher. In addition, the forest canopy structure parameters, such as the average height of the forest stand extracted from UAV-LiDAR data, had a significant impact on the estimation of forest age. Thus, when the combined Sentinel-2 and LiDAR data were used to establish these parameters, the highest accuracy in the estimation of Masson pine was obtained. The findings of this study provide new insights for forest age estimation based on multi-source remote sensing data.

Abstract To prevent the spread of pine wilt disease (PWD), a transportable carbonization equipment was designed for in-situ treatment of infected pine wood (IPW). The equipment killed all pine wood nematodes (PWNs) in IPW when carbonization temperature was up to 200 °C. The optimal laboratory process of infected pine wood charcoal (IPWC) was carbonization temperature of 500 °C, heating rate of 3 °C min−1 and holding time of 0 min. Based on the optimal laboratory process, the transportable carbonization equipment produced IPWC with a fixed carbon content of 79.82%, and ash content of 1.14% and a moisture content of 7.83%, which meets the requirements of EN 1860-2:2005(E) standard. The economic efficiency of incineration (T1 mode), crushing (T2 mode), and transportable carbonization (T3 mode) was evaluated. For each ton of IPW treatment, the profit generated was −75.48 USD in T1 mode, 26.28 USD in T2 mode, and 51.91 USD in T3 mode. T3 mode had the highest economic efficiency. These findings will be helpful to provide guidance for the control of PWD and value-added utilization of IPW. Graphical Abstract

To prevent the spread of pine wilt disease (PWD), a transportable carbonization equipment was designed for in-situ treatment of infected pine wood (IPW). The equipment killed all pine wood nematodes (PWNs) in IPW when carbonization temperature was up to 200 °C. The optimal laboratory process of infected pine wood charcoal (IPWC) was carbonization temperature of 500 °C, heating rate of 3 °C min−1 and holding time of 0 min. Based on the optimal laboratory process, the transportable carbonization equipment produced IPWC with a fixed carbon content of 79.82%, and ash content of 1.14% and a moisture content of 7.83%, which meets the requirements of EN 1860-2:2005(E) standard. The economic efficiency of incineration (T1 mode), crushing (T2 mode), and transportable carbonization (T3 mode) was evaluated. For each ton of IPW treatment, the profit generated was −75.48 USD in T1 mode, 26.28 USD in T2 mode, and 51.91 USD in T3 mode. T3 mode had the highest economic efficiency. These findings will be helpful to provide guidance for the control of PWD and value-added utilization of IPW. Highlights: A transportable carbonization equipment was designed for in-situ treatment of IPWs The transportable carbonization equipment killed all PWNs of IPW when carbonization temperature was up to 200 °C. In the transportable carbonization mode, the income generated from treating each ton of IPW was 51.91 USD. [ABSTRACT FROM AUTHOR]

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury (Hg) trends, but with the large knowledge gaps in the reliability. In this study, we comprehensively evaluated the Hg source, radial translocation and age effect of Masson pine (Pinus massoniana) tree ring at Mt. Jinyun in Chongqing, to assess the suitability of such tree ring as the archive of atmospheric Hg. Results showed that distinct variabilities among Masson pine tree-ring Hg concentration profiles. The Hg concentration significantly increased along with stem height (P < 0.05), indicating the Hg in tree rings mainly derived from foliage uptake atmospheric Hg. We found a distinct age effect that the tree ring of young trees had the higher Hg concentration. Besides, we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree rings. The modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in Chongqing. We finally suggest that in further Hg dendrochemistry, better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect. [Display omitted] [ABSTRACT FROM AUTHOR]

The tensile mechanical behavior of water-saturated earlywood (EW) and latewood (LW) within the same growth ring of Masson pine (Pinus massoniana) was investigated in the hydrothermal environment and discussed with respect to the density and microfibril angle (MFA) of the wood specimens. The tensile modulus, tensile strength, and strain at failure of EW and LW in the longitudinal (L) and tangential (T) directions were determined at different temperature levels ranging from 30 °C to 80 °C. Major differences in the tensile mechanical properties were found between EW and LW in the L and T directions. Compared to LW, EW showed a smaller density and a larger MFA, resulting in a lower tensile modulus, lower tensile strength, and higher strain at failure. Compared to the L specimens, the T specimens showed lower tensile modulus, lower tensile strength, and higher strain at failure. As the hygrothermal temperature increased, the MFAs, tensile modulus, and tensile strength of EW and LW specimens decreased, except for the MFAs of LW, while the strain at failure of the specimens showed the opposite trend. Variations in the tensile mechanical behavior between EW and LW were mainly influenced by the density and MFA of the specimens, and are closely associated with the hydrothermal softening properties of wood. These findings contribute to a further understanding of the structural–mechanical relationships of Masson pine wood at the cell wall level, and provide a scientific basis for the better utilization of plantation softwood in the hydrothermal environment. [ABSTRACT FROM AUTHOR]

Heavy metal pollution of the soil affects the environment and human health. Masson pine is a good candidate for phytoremediation of heavy metal in mining areas. Microorganisms in the rhizosphere can help with the accumulation of heavy metal in host plants. However, studies on its rhizosphere bacterial communities under heavy metal pollution are still limited. Therefore, in this study, the chemical and bacterial characteristics of Masson pine rhizosphere under four different levels of heavy metal pollution were investigated using 16 S rRNA gene sequencing, soil chemistry and analysis of plant enzyme activities. The results showed that soil heavy metal content, plant oxidative stress and microbial diversity damage were lower the farther they were from the mine dump. The co-occurrence network relationship of slightly polluted soils (C1 and C2) was more complicated than that of highly polluted soils (C3 and C4). Relative abundance analysis indicated Sphingomonas and Pseudolabrys were more abundant in slightly polluted soils (C1 and C2), while Gaiella and Haliangium were more abundant in highly polluted soils (C3 and C4). LEfSe analysis indicated Burkholderiaceae, Xanthobacteraceae, Gemmatimonadaceae, Gaiellaceae were significantly enriched in C1 to C4 site, respectively. Mantel analysis showed that available cadmium (Cd) contents of soil was the most important factor influencing the bacterial community assembly. Correlation analysis showed that eight bacterial genus were significantly positively associated with soil available Cd content. To the best of our knowledge, this is the first study to investigate the rhizospheric bacterial community of Masson pine trees under different degrees of heavy metal contamination, which lays the foundation for beneficial bacteria-based phytoremediation using Masson pines in the future.

Aims: Soil metabolites have a great influence on regulating the growth and development of plants and microbes in forest ecosystems. This study aims to reveal the characteristic metabolite profiles and their enriched metabolic pathways in the rhizosphere soil of Masson pine plantations at three different ages. Method: The rhizosphere soil of Masson pine from 10, 31, and 52 years plantation was collected. The metabolites were analyzed using a soil pseudotargeted metabolomics approach and then the relationships between soil metabolites and chemical properties, enzyme activities were established. Results: A total of 172 rhizosphere soil metabolites in 26 classes were identified. There was a decreasing trend in the total concentration of rhizosphere soil metabolites with increasing stand age. Seventy-two characteristic metabolites were screened, mainly saccharides, fatty acids, amino acids, phenolic acids, polyols and terpenoids. Among them, benzoic acid and galactonic acid contributed the most to the young forest, and stearic acid had the greatest influence on the near-mature forest plantation. Erythritol had great effects on the mature forest plantation. Seven metabolic pathways changed with increasing stand age. Correlation analysis showed that available potassium (AK) and soil alkaline protease (S-ALPT) were significantly positively correlated with phenolic acids, polyhydroxy carboxylic acids, etc. Conclusion: The rhizosphere soil of Masson pine had different metabolite profiles at different developmental stages, and the soil nutrient pools were effectively improved. These results provide a reference for plantation management in Masson pine and a deeper understanding of forest metabolic characteristics. [ABSTRACT FROM AUTHOR]

Tree species composition in forest ecosystems is an important biological factor affecting the diversity of ectomycorrhizal fungi (EMF). However, little is known about the composition and diversity of EMF communities associated with Pinus massoniana in different P. massoniana association habitats (MpAHs) in subtropical mountains. This study investigated the EMF community characteristics of P. massoniana in different MpAHs using plant community surveys, soil property analyses, and mycorrhizal identification. A total of 56 operational taxonomic units (OTUs), belonging to 20 families and 22 genera, were identified. OTU richness of Basidiomycota (58.93%) was higher than that of Ascomycota (41.07%). Unclassified Helotiales, Russula, Lactarius, and Tomentella were the dominant groups. Different stand types significantly altered the EMF communities of P. massoniana (p < 0.05, for Shannon index) and the associations of P. massoniana + Populus adenopoda (Mp_Pa) had the highest diversity of EMF, while P. massoniana + Cunninghamia lanceolata (Mp_Cl) had the lowest diversity. The number of specific OTUs was higher than shared OTUs. Similarity index and principal coordinate analysis indicated that the EMF communities of P. massoniana varied significantly in different MpAHs (R2 = 0.21, p = 0.001). The linear regression model showed that the EMF diversity of P. massoniana was positively related to tree species diversity, indicating that the EMF diversity of P. massoniana is influenced by tree species diversity. The findings provide a reasonable reference for tree species configuration in the process of mixed transformation or near-natural management of plantations. [ABSTRACT FROM AUTHOR]

Pine wilt disease, caused by Bursaphelenchus xylophilus, is a highly destructive and contagious forest affliction. Often termed the “cancer” of pine trees, it severely impacts the growth of Masson pine (Pinus massoniana). Previous studies have demonstrated that ectopic expression of the PmACRE1 gene from P. massoniana in Arabidopsis thaliana notably enhances resistance to pine wilt nematode infection. To further elucidate the transcriptional regulation and protein interactions of the PmACRE1 in P. massoniana in response to pine wilt nematode infection, we cloned a 1984 bp promoter fragment of the PmACRE1 gene, a transient expression vector was constructed by fusing this promoter with the reporter GFP gene, which successfully activated the GFP expression. DNA pull-down assays identified PmMYB8 as a trans-acting factor regulating PmACRE1 gene expression. Subsequently, we found that the PmACRE1 protein interacts with several proteins, including the ATP synthase CF1 α subunit, ATP synthase CF1 β subunit, extracellular calcium-sensing receptor (PmCAS), caffeoyl-CoA 3-O-methyltransferase (PmCCoAOMT), glutathione peroxidase, NAD+-dependent glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase 1, cinnamyl alcohol dehydrogenase, auxin response factor 16, and dehydrin 1 protein. Bimolecular fluorescence complementation (BiFC) assays confirmed the interactions between PmACRE1 and PmCCoAOMT, as well as PmCAS proteins in vitro. These findings provide preliminary insights into the regulatory role of PmACRE1 in P. massoniana’s defense against pine wilt nematode infection.

Masson pine (Pinus massoniana Lamb.) is a dominant coniferous species in southern China, known for its rapid growth, abundant yield, and extensive utilization. Despite the robust adaptability of Masson pine and the rich annual precipitation in its distribution areas, this species still faces the mortality risk caused by the recurrent high temperatures in summer and low precipitation in subtropical regions. The mortality risk of Masson pine may increase in the future when facing a more frequent or intensive drought threat due to climate change. In this study, we conducted a manipulated drought experiment accompanying high temperature (~32.3 ± 0.7 °C in daytime and 28 °C in nighttime) to simulate a flash drought, aiming to explore the composite physiological response (hydraulic, gas exchange, and nonstructural carbon (NSC) characteristics) of Masson pine seedlings to extreme drought characterized by a high intensity and long duration. We found that, as the drought developed, the leaf water potential and gas exchange traits (net photosynthesis rate, stomatal conductance, and transpiration) significantly decreased while the percentage loss of hydraulic conductivity (PLC) significantly increased. In contrast, NSC remained a more constant trend before it was significantly reduced on day 30 after the beginning of the drought. Except for NSC, all the other traits had significant correlations between them. Additionally, hydraulic dysfunction indicated by the increasing PLC preceded the NSC depletion, which may indicate a more significant role for hydraulic failure than carbon starvation in drought-induced mortality. Conclusively, hydraulic and gas exchange traits showed a coupling response to drought, but NSC displayed an independent dynamic. The findings may improve our understanding of drought-coping strategies of Masson pine and provide some theoretical basis for Masson pine forest management. [ABSTRACT FROM AUTHOR]

Masson pine (Pinus massoniana Lamb.) is a major fast-growing woody tree species and pioneer species for afforestation in barren sites in southern China. However, the regulatory mechanism of gene expression in P. massoniana under drought remains unclear. To uncover candidate microRNAs, their expression profiles, and microRNA-mRNA interactions, small RNA-seq was used to investigate the transcriptome from seedling roots under drought and rewatering in P. massoniana. A total of 421 plant microRNAs were identified. Pairwise differential expression analysis between treatment and control groups unveiled 134, 156, and 96 differential expressed microRNAs at three stages. These constitute 248 unique microRNAs, which were subsequently categorized into six clusters based on their expression profiles. Degradome sequencing revealed that these 248 differentially expressed microRNAs targeted 2069 genes. Gene Ontology enrichment analysis suggested that these target genes were related to translational and posttranslational regulation, cell wall modification, and reactive oxygen species scavenging. miRNAs such as miR482, miR398, miR11571, miR396, miR166, miRN88, and miRN74, along with their target genes annotated as F-box/kelch-repeat protein, 60S ribosomal protein, copper-zinc superoxide dismutase, luminal-binding protein, S-adenosylmethionine synthase, and Early Responsive to Dehydration Stress may play critical roles in drought response. This study provides insights into microRNA responsive to drought and rewatering in Masson pine and advances the understanding of drought tolerance mechanisms in Pinus. [ABSTRACT FROM AUTHOR]

Screw connection is a type most commonly applied to timber structures. As important commercial tree species in China, Masson pine and Chinese fir have the potential to prepare wood structures. In this study, the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored. The results showed that: (1) The nail holding strength of the tangential section was the maximum, followed by that of the radial section, and that of the cross section was the minimum. (2) The nail holding strength of Masson pine was higher than that of Chinese fir. (3) The nail holding strength grew with the increase in the diameter of self-tapping screws, but a large diameter would lead to plastic cracking of the timber, thus further affecting the nail holding strength. Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm. (4) Under a large diameter of screws, prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength. (5) Prefabricated guiding bores were more necessary for the screw connection of Masson pine. The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures. [ABSTRACT FROM AUTHOR]

Masson pine (Pinus massoniana Lamb.) is an important resin-producing conifer species in China. Resin yield is a highly heritable trait and varies greatly among different genotypes. However, the mechanisms regulating the resin yield of masson pine remain largely unknown. In this study, physiological, proteomic, and gene expression analysis was performed on xylem tissues of masson pine with high and low resin yield. Physiological investigation showed that the activity of terpene synthase, as well as the contents of soluble sugar, jasmonic acid (JA), methyl jasmonate (MeJA), gibberellins (GA1, GA4, GA9, GA19, and GA20), indole-3-acetic acid (IAA), and abscisic acid (ABA) were significantly increased in the high yielder, whereas sucrose and salicylic acid (SA) were significantly decreased compared with the low one. A total of 2984 differentially expressed proteins (DEPs) were identified in four groups, which were mainly enriched in the biosynthesis of secondary metabolites, protein processing in the endoplasmic reticulum, carbohydrate metabolism, phytohormone biosynthesis, glutathione metabolism, and plant-pathogen interaction. Integrated physiological and proteomic analysis revealed that carbohydrate metabolism, terpenoid biosynthesis, resistance to stress, as well as JA and GA biosynthesis and signaling, play key roles in regulating resin yield. A series of proteins associated with resin yield, e.g., terpene synthase proteins (TPSs), ATP-binding cassette transporters (ABCs), glutathione S-transferase proteins (GSTs), and heat shock proteins (HSPs), were identified. Resin yield-related gene expression was also associated with resin yield. Our study unveils the implicated molecular mechanisms regulating resin yield and is of pivotal significance to breeding strategies of high resin-yielding masson pine cultivars. [ABSTRACT FROM AUTHOR]

The mechanisms underlying plant response to drought involve the expression of numerous functional and regulatory genes. Transcriptome sequencing based on the second- and/or third-generation high-throughput sequencing platforms has proven to be powerful for investigating the transcriptional landscape under drought stress. However, the full-length transcriptomes related to drought responses in the important conifer genus Pinus L. remained to be delineated using the third-generation sequencing technology. With the objectives of identifying the candidate genes responsible for drought and/or rehydration and clarifying the expression profile of key genes involved in drought regulation, we combined the third- and second-generation sequencing techniques to perform transcriptome analysis on seedling roots under drought stress and rewatering in the drought-tolerant conifer Pinus massoniana Lamb. A sum of 294,114 unique full-length transcripts were produced with a mean length of 3217 bp and N50 estimate of 5075 bp, including 279,560 and 124,438 unique full-length transcripts being functionally annotated and Gene Ontology enriched, respectively. A total of 4076, 6295 and 18,093 differentially expressed genes (DEGs) were identified in three pair-wise comparisons of drought-treatment versus control transcriptomes, including 2703, 3576 and 8273 upregulated and 1373, 2719 and 9820 downregulated DEGs, respectively. Moreover, 157, 196 and 691 DEGs were identified as transcription factors in the three transcriptome comparisons and grouped into 26, 34 and 44 transcription factor families, respectively. Gene Ontology enrichment analysis revealed that a remarkable number of DEGs were enriched in soluble sugar-related and cell wall-related processes. A subset of 75, 68 and 97 DEGs were annotated to be associated with starch, sucrose and raffinose metabolism, respectively, while 32 and 70 DEGs were associated with suberin and lignin biosynthesis, respectively. Weighted gene co-expression network analysis revealed modules and hub genes closely related to drought and rehydration. This study provides novel insights into root transcriptomic changes in response to drought dynamics in Masson pine and serves as a fundamental work for further molecular investigation on drought tolerance in conifers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Wildland Fire Science is the property of Journal of Wildland Fire Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Masson pine natural forests are ecologically and economically valuable forest ecosystems extensively distributed across China. However, they have been subject to deforestation due to human disturbance. Moreover, climate change affects the growth, mortality, and recruitment of forests, yet available forest growth models do not effectively analyze the impacts of climate. A climate-sensitive transition matrix model (CM) was developed using data from 330 sample plots collected during the 7th (2004), 8th (2009), and 9th (2014) Chinese National Forest Inventories in Hunan Province. To assess model robustness, two additional models were created using the same data: a non-climate-sensitive transition matrix model (NCM) and a fixed probability transition matrix model (FM). The models were compared using tenfold cross-validation and long-term predictive performance analysis. The cross-validation results did not show any significant differences among the three models, with the FM performing slightly better than the NCM. However, the application of the CM for long-term prediction (over a span of 100 years) under three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5) revealed distinct dynamics that demonstrated enhanced reliability. This is attributed to the consideration of climate variables that impact forest dynamics during long-term prediction periods. The CM model offers valuable guidance for the management of Masson pine natural forests within the context of changing climatic conditions. [ABSTRACT FROM AUTHOR]

Ecological stoichiometry plays important roles in understanding the nutrient constraints on tree growth and development, as well in maintaining ecosystem services in forests, yet the characteristics of carbon:nitrogen:phosphorous (C:N:P) stoichiometry in forests under karst environment have not been sufficiently evaluated. In this study, concentration, distribution, stocks of Nitrogen (N) and Phosphorous (P), and ecological stoichiometry were studied in three common forest types: Masson pine natural forests (MPNF), Masson pine plantation forests (MPPF), and Slash pine plantation forests (SPPF) in a karst region of southwestern China. Results showed that N concentrations were higher in overstory than in understory and litter in the studied forests. However, P concentration was relatively low in overstory component of the forested ecosystems. Meanwhile, the N and P concentrations were higher in SPPF in the stem and litter, while these contents were higher in MPPF and MPNP in the overstory and understory. The N and P stocks ranged from 5.7–6.2 t ha−1, and 0.5–0.6 t ha−1 in the examined forests. The ecological stoichiometry of C:N:P in the three forest types was similar in litter (46–49:2:1), and relatively steady in soil (250–320:13–16:1) and tree leaf (100–200:14–20:1). Soil P status was the primary limiting factor in affecting tree growth in MPPF and SPPF (N:P ratio > 16), while both N and P conditions were the main restrictive factors in MPNP (N:P ratio = 15) in the study area. Our study provides scientific references and useful datasets of C:N:P stoichiometry for sustainable management of forest ecosystems in karst regions. [ABSTRACT FROM AUTHOR]

Downed woody debris (DWD) can alter the chemical and biological properties of forest soils, and this process is affected by the degree of DWD decay. Our aim was to assess the effects of the entire decay process of DWD on the associated soil microbial communities. Here, we examined the differences in soil microbial community size and composition among five decay stages (DC Ⅰ–Ⅴ) of Masson pine (Pinus massoniana Lamb.) at two soil depths in a climate transitional forest and then linked these differences to soil chemical properties. The decay of DWD increased soil total PLFAs, and the complexity of soil microbial networks was highest in stage Ⅱ and then decreased with the decay stage. The relative abundance of fungi increased with the decay stage, while the relative abundance of gram-positive bacteria decreased with the decay stage. The microbial community composition at a soil depth of 0–10 cm was mainly driven by soil pH and organic C (SOC), and at a depth of 10–20 cm, soil pH was the primary determinant of microbial community composition. Our findings suggest that DWD decomposition reduces microbial physiological stress, promotes fungal growth, and stimulates microbial biomass, highlighting the positive impact of DWD on forest soils. Future research is needed to elucidate the universal effects of DWD decomposition on soil properties, especially focusing on the response of soil microbial processes to the decomposition time of DWD. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biochar has been considered as a cost-effective amendment to improve the soil water content and thus to mitigate the effects of drought on plants. However, less is known about the mitigating effects of biochar application on the negative effect of longer drought duration on trees. We investigated the effects of drought duration in combination with biochar application on the growth, tissue non-structural carbohydrate (NSC) concentrations, needle photosynthesis, and δ13C content of 1-year-old Pinus massoniana saplings in a greenhouse experiment. We found that the height and total biomass of P. massoniana saplings were significantly decreased with increasing drought duration, which was likely attributed to the suppressed photosynthetic capacity. The longer drought duration (e.g., 1 month) significantly decreased needle photosynthesis and increased the value of needle δ13C but did not deplete tissue NSC concentrations at the expense of growth, suggesting that plants prioritize carbon storage over growth in response to a long duration of drought. Surprisingly, the application of biochar significantly decreased the survival of P. massoniana saplings and aggravated the negative effect of drought duration on the growth of P. massoniana, which is probably attributed to the increased soil pH value of >7.5, as P. massoniana is adapted to mildly acid to neutral soils. Our results suggest that the effect of biochar application might be species specific, and it can aggravate the negative effect of drought duration on plants that are less tolerant to alkaline soils.

Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) exhibits robust cloning and propagation capabilities, enabling its expansion into adjacent forest communities. However, previous studies on Moso bamboo expansion have predominantly focused on virgin forests, and studies on its effects on planted forests, particularly adjacent coniferous forests, remain limited. Therefore, this study investigated the effect of Moso bamboo expansion into planted forests of Masson pine (Pinus massoniana Lamb.) on soil metabolites. The study was conducted using untargeted metabolomics under different slope directions and positions in a typical karst river basin, and the relationships with soil metabolites and environmental factors were delineated. Moso bamboo expansion primarily affected glycerophospholipid metabolism and flavonoid biosynthesis in the soil. The alpha diversity of soil metabolites increased with the slope position (p < 0.05). However, no significant difference in soil metabolites was observed between different slopes. The effects of soil organic matter, total phosphorus, and soil microbial community composition on soil metabolites were significant (p < 0.05). Structural equation modeling suggested the existence of these two potential pathways of influence; the slope position and direction jointly affected soil metabolism through soil properties including pH (37.6 %), OM (49.3 %), Ca (14.4 %), HN (10.1 %), and TP (10.4 %), and microbial communities by Observed Species (19.3 %), Chao1 (12.3 %), ACE (12.1 %), and Shannon indices (20.3 %). Furthermore, the influence of slope positions and directions directly affected soil properties, subsequently affecting soil metabolism through the mediation of soil microbial communities by Observed Species (70.6 %), Chao1 (59.9 %), ACE (57.9 %), and Shannon indices (52.5 %). Therefore, we propose that assessing the rapid response on soil metabolites under varying slope positions and directions, along with their connection to soil environmental indicators, may provide insight into the ecological implications of Moso bamboo expansion. Our findings provide valuable insights for understanding how Moso bamboo cover dynamics affect soil metabolites in a typical karst river basin. [Display omitted] • Moso bamboo expansion influences the equilibrium of planted forest ecosystems. • Moso bamboo expansion affects soil metabolite variations. • Glycerophospholipid metabolism and flavonoid biosynthesis in soil are significantly enriched. • Slope direction and position indirectly affect soil metabolism. • Soil metabolomics reveals the interaction that occur in soil ecosystems. [ABSTRACT FROM AUTHOR]

Plant metabolism is an important functional trait, and its metabolites have physiological and ecological functions to adapt to the growth environment. However, the physiological and ecological functions of metabolites from different provinces of the same plant species are still unclear. Therefore, this study aimed to determine whether metabolites from different provinces of Masson pine (Pinus massoniana Lamb.) have the corresponding metabolic traits. The gas chromatography–mass spectrometry technique and metabonomic analysis methods were used to characterize 35 Masson pine half-sib families from two provinces. A total of 116 metabolites were putatively identified in 35 families of Masson pine, among which the average content of organic acids was the highest, followed by saccharides and alcohols, and phosphoric acids. Comparative analysis of metabolite groups showed that organic acids, amines, and others were significantly different between the Masson pine families from Guangxi and Guizhou provinces. Six differential metabolites were found between the provinces from Guizhou and Guangxi, namely caffeic acid, L-ascorbic acid, gentiobiose, xylitol, d-pinitol, and β-sitosterol. The most significantly enriched pathways among differentially expressed metabolites between the two provinces were steroid biosynthesis, phenylpropanoid biosynthesis, glutathione metabolism, pentose and glucuronate interconversions. Overall, the results showed that Masson pine half-sib families from different geographical provinces have different metabolite profiles and their metabolites are affected by geographical provenance and growth environment adaptability. This study revealed that the breeding of Masson pine families from different provinces changed the metabolite profiles, providing a reference for the multipurpose breeding of Masson pine.

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Masson pine (Pinus massoniana L.) is one of the most important resin-producing tree species in southern China. However, the molecular regulatory mechanisms of resin yield are still unclear in masson pine. In this study, an integrated analysis of transcriptome, proteome, and biochemical characteristics from needles of masson pine with the high and common resin yield was investigated. The results showed that chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl C), carotenoids (Car), glucose (Glu), gibberellin A9 (GA9), gibberellin A15 (GA15), and gibberellin A53 (GA53) were significantly increased, whereas fructose (Fru), jasmonic acid (JA), jasmonoyl-L-isoleucine (JA-ILE), gibberellin A1 (GA1), gibberellin A3 (GA3), gibberellin A19 (GA19), and gibberellin A24 (GA24) were significantly decreased in the high resin yield in comparison with those in the common one. The integrated analysis of transcriptome and proteome showed that chlorophyll synthase (chlG), hexokinase (HXK), sucrose synthase (SUS), phosphoglycerate kinase (PGK), dihydrolipoamide dehydrogenase (PDH), dihydrolipoamide succinyltransferase (DLST), 12-oxophytodienoic acid reductase (OPR), and jasmonate O-methyltransferases (JMT) were consistent at the transcriptomic, proteomic, and biochemical levels. The pathways of carbohydrate metabolism, terpenoid biosynthesis, photosynthesis, and hormone biosynthesis may play crucial roles in the regulation of resin yield, and some key genes involved in these pathways may be candidates that influence the resin yield. These results provide insights into the molecular regulatory mechanisms of resin yield and also provide candidate genes that can be applied for the molecular-assisted selection and breeding of high resin-yielding masson pine. [ABSTRACT FROM AUTHOR]

Low light and drought often limit the growth and performance of Masson pines (Pinus massoniana) in the subtropical forest ecosystem of China. We speculated that stress-induced defensive secondary metabolites, such as flavonoids and terpenoids, might influence the growth of Masson pines, considering the existence of tradeoffs between growth and defense. However, the mechanisms of Masson pines responsive to low light and drought at the levels of these two metabolites remain unclear. In the present work, the compositions of flavonoids and terpenoids, as well as their biosynthetic pathways, were revealed through metabolome and transcriptome analyses, respectively, coupled with a study on carbon allocation using a 13CO2-pulse-labeling experiment in two-year-old seedlings under low light (LL), drought (DR), and their combined stress (DL) compared to a control (CK). A total of 35 flavonoids and derivatives (LL vs. CK: 18; DR vs. CK: 20; and DL vs. CK: 18), as well as 29 terpenoids and derivatives (LL vs. CK: 23; DR vs. CK: 13; and DL vs. CK: 7), were differentially identified in the leaves. Surprisingly, most of them were decreased under all three stress regimes. At the transcriptomic level, most or all of the detected DEGs (differentially expressed genes) involved in the biosynthetic pathways of flavonoids and terpenoids were downregulated in phloem and xylem under stress treatments. This indicated that stress treatments limited the production of flavonoids and terpenoids. The reduction in the 13C allocation to stems might suggest that it is necessary for maintaining the growth of Masson pine seedlings at the whole-plant level by attenuating energetic resources to the biosynthetic pathways of flavonoids and terpenoids when facing the occurrence of adverse environments. Our results provide new insight into understanding the acclimation strategy of Masson pines or other conifers in adverse environments. [ABSTRACT FROM AUTHOR]

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Premise: Competition is an important driver of tree mortality and thus affects forest structure and dynamics. Tree architectural traits, such as height‐to‐diameter (H‐D) and branch length‐to‐diameter (L‐d) relationships are thought to influence species competitiveness by affecting light capture. Unfortunately, little is known about how the H vs. D and L vs. d scaling exponents are related to tree performance (defined in the context of growth vigor) in competition. Methods: Using data from field surveys of 1547 individuals and destructive sampling of 51 trees with 1086 first‐order branches from a high‐density Pinus massoniana forest, we explored whether the H vs. D and the L vs. d scaling exponents respectively differed numerically across tree performance and branch vertical position in crowns. Results: The results indicated that (1) the H vs. D scaling exponent decreased as tree performance declined; (2) the L vs. d scaling exponent differed across tree performance classes (i.e., the scaling exponent of "inferior" trees was significantly larger than that of "moderate" and "superior" trees); (3) the L vs. d scaling exponent decreased as branch position approached ground level; and (4) overall, the branch scaling exponent decreased as tree performance improved in each crown layer, but decreased significantly in the intermediate layer. Conclusions: This study highlights the variation within (and linkage among) length‐to‐diameter scaling relationships across tree performance at the individual and branch levels. This linkage provides new insights into potential mechanisms of tree growth variation (and even further mortality) under competition in subtropical forests. [ABSTRACT FROM AUTHOR]

Ecological stoichiometry plays important roles in understanding the nutrient constraints on tree growth and development, as well in maintaining ecosystem services in forests, yet the characteristics of carbon:nitrogen:phosphorous (C:N:P) stoichiometry in forests under karst environment have not been sufficiently evaluated. In this study, concentration, distribution, stocks of Nitrogen (N) and Phosphorous (P), and ecological stoichiometry were studied in three common forest types: Masson pine natural forests (MPNF), Masson pine plantation forests (MPPF), and Slash pine plantation forests (SPPF) in a karst region of southwestern China. Results showed that N concentrations were higher in overstory than in understory and litter in the studied forests. However, P concentration was relatively low in overstory component of the forested ecosystems. Meanwhile, the N and P concentrations were higher in SPPF in the stem and litter, while these contents were higher in MPPF and MPNP in the overstory and understory. The N and P stocks ranged from 5.7–6.2 t ha−1, and 0.5–0.6 t ha−1 in the examined forests. The ecological stoichiometry of C:N:P in the three forest types was similar in litter (46–49:2:1), and relatively steady in soil (250–320:13–16:1) and tree leaf (100–200:14–20:1). Soil P status was the primary limiting factor in affecting tree growth in MPPF and SPPF (N:P ratio > 16), while both N and P conditions were the main restrictive factors in MPNP (N:P ratio = 15) in the study area. Our study provides scientific references and useful datasets of C:N:P stoichiometry for sustainable management of forest ecosystems in karst regions.

Developing green pretreatment technologies that prioritize the selective separation of lignin is of significant importance for the industrialization of biorefining. This work employed H 2 SO 4 -catalyzed γ-valerolactone (GVL) pretreatment on masson pine sawdust (GAM) to investigate process conditions and the enzymatic hydrolysis performance of masson pine. The results indicated that the lignin removal rate was 87.2% under the optimal pretreatment conditions (150ºC, 75 mM H 2 SO 4). The synergistic effect of the H 2 SO 4 catalyst and GVL pretreatment resulted in an enzymatic hydrolysis yield for GAM (76.8%) nearly six times higher than that of other non-synergistic systems (5.7%∼13.0%). Furthermore, the enzymatic hydrolysis yield increased to 97.3% upon the addition of bovine serum albumin. Microscopic visualization was used to analyze the morphological changes of cells and the micro-distribution of lignin within GAM cell walls after pretreatment. Additionally, structural changes in the molecular weight, functional groups, and linkage contents of GAM lignin were analyzed. This research provides valuable insights for masson pine in producing fermentable monosaccharides and acquiring lignin with enhanced processing properties. [Display omitted] • Studied the H 2 SO 4 -catalyzed GVL pretreatment under lignin-first strategy. • Proved the synergistic effect of H 2 SO 4 catalyst and GVL extraction. • The yield of converting masson pine waste into fermentable glucose can reach 97.3%. • Lignin's migration and structure changes under H 2 SO 4 -catalyzed GVL pretreatment. [ABSTRACT FROM AUTHOR]

Heavy metal pollution of the soil affects the environment and human health. Masson pine is a good candidate for phytoremediation of heavy metal in mining areas. Microorganisms in the rhizosphere can help with the accumulation of heavy metal in host plants. However, studies on its rhizosphere bacterial communities under heavy metal pollution are still limited. Therefore, in this study, the chemical and bacterial characteristics of Masson pine rhizosphere under four different levels of heavy metal pollution were investigated using 16 S rRNA gene sequencing, soil chemistry and analysis of plant enzyme activities. The results showed that soil heavy metal content, plant oxidative stress and microbial diversity damage were lower the farther they were from the mine dump. The co-occurrence network relationship of slightly polluted soils (C1 and C2) was more complicated than that of highly polluted soils (C3 and C4). Relative abundance analysis indicated Sphingomonas and Pseudolabrys were more abundant in slightly polluted soils (C1 and C2), while Gaiella and Haliangium were more abundant in highly polluted soils (C3 and C4). LEfSe analysis indicated Burkholderiaceae, Xanthobacteraceae, Gemmatimonadaceae, Gaiellaceae were significantly enriched in C1 to C4 site, respectively. Mantel analysis showed that available cadmium (Cd) contents of soil was the most important factor influencing the bacterial community assembly. Correlation analysis showed that eight bacterial genus were significantly positively associated with soil available Cd content. To the best of our knowledge, this is the first study to investigate the rhizospheric bacterial community of Masson pine trees under different degrees of heavy metal contamination, which lays the foundation for beneficial bacteria-based phytoremediation using Masson pines in the future. [Display omitted] • Sphingomonas, Bradyrhizobium and Haliangium were dominated in pine rhizosphere. • Bacterial network of HM polluted soil was simpler than that of clean soil. • Gaiella and Haliangium were representative taxa in HM polluted soils. • Soil available Cd was the most important factor influencing bacterial community. • Plant antioxidant was positively correlated with soil heavy metals. [ABSTRACT FROM AUTHOR]

Background: With active physiological and biochemical activities, tissue-specific protoplasts from cambial derivatives, could serve as a specific source for information on xylogenesis for softwood species resistant to stable genetic transformation and lacking available mutants. Methods and results: In this study, protoplasts were isolated from developing xylem of the Chinese red pine, Pinus massoniana, by enzymolysis. High-quality RNAs were extracted from developing xylem and their protoplasts for constructing transcriptome libraries. Using Illumina HiSeq 2500 PE150 platform, a total of 362,328,426 clean paired-end reads (54.35G) were generated from multiple cDNA libraries and assembled into 146,422 unigenes. The transcriptome data were further analysed to identify 1567 differentially expressed genes (DEGs) between the isolated protoplasts and developing xylem of P. massoniana (Masson pine), 1126 DEGs were upregulated in protoplasts relative to developing xylem cells and 441 were downregulated. Most of the differentially expressed genes in biological process terms are related to plant response, which may be due to the response to cell wall removal. Further, the expression pattern of 71 unigenes involved in lignin biosynthesis was verified by RNA-seq. Conclusions: This study is the first to report the transcriptome profiles of the developing xylem and its protoplasts of coniferous trees, which provide a new perspective and valuable resource for tracking transcriptional regulatory events in wood formation of Masson pine. [ABSTRACT FROM AUTHOR]

Aims: Pinus massoniana Lamb. is a widely distributed native species and afforestation pioneer tree in the subtropical forests of China; however, the species' quality and productivity are significantly affected by phosphorus (P) deficiency. Although ectomycorrhizal (ECM) fungi can enhance plant adaptation to nutrient deficiency, the interactive effects of ECM fungi colonization and P availability on physiological responses and nutrient uptake in P. massoniana seedlings remain unknown. Method: We compared the physiological response and nutrient absorption of uninoculated P. massoniana seedlings and seedlings inoculated with Suillus luteus or S. bovinus under three P supplies (P deficiency, 0.01 mM/L; medium P, 0.1 mM/L; and P sufficiency, 1 mM/L) in sand culture. Results: P deficiency limited the seedlings growth and nutrient content but increased the antioxidant enzyme activity. S. luteus and S. bovinus significantly increased the seedlings growth under P deficiency. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) as well as the contents of malondialdehyde (MDA) and proline of inoculated and uninoculated seedlings were significantly higher under P deficiency than P sufficiency. Under P deficiency, POD and SOD activities increased with time and were higher in inoculated seedlings; however, proline contents were lower in inoculated seedlings. P deficiency decreased the P and potassium (K) contents in the roots, stems, and leaves of seedlings. Moreover, under P deficiency, S. luteus significantly improved P content in stems and leaves, whereas S. bovinus significantly improved K content in leaves. Conclusion: ECM fungi increased SOD and POD activities and improved P and K absorption in P. massoniana seedlings in response to P deficiency. [ABSTRACT FROM AUTHOR]

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Urban green space has been implicated in shaping airborne microbes, but there is an only rudimentary understanding of the key factors of urban green space affecting the composition and structures of airborne microbes. Here, we selected 40 urban sites based on stratified random sampling design and investigated the effects of multiple factors including landscapes, plant, soil, and anthropogenic factors on airborne microbial communities, especially bacterial and fungal pathogens. Bacterial and fungal communities in the control area with lower greenness were significantly (P 30% masson pine. Together, these results provide insights into the importance of green space for providing health benefits for city dwellers by reducing pathogens in air, as well as providing support for the inclusion of plant species in the management of urban green space to reduce exposure risk of airborne pathogens.

This study addressed the effects of climate drivers on the tree-ring width (TRW) parameters (total ring width (TR), earlywood width (EW) and latewood width (LW)) and the total ring δ13C series of different wood components (whole wood, α-cellulose and holocelluose) from Masson pine in subtropical China. Pairwise correlation coefficients between three ring width parameters were statistically significant. EW and LW did not reveal much stronger climate sensitivity rather than TR. This indicated that the use of intra-annual ring width has little benefit in extracting more climate information. The mean δ13C series of the three components of the total ring had the strongest climate response to the July–September relative humidity (r = −0.792 (whole wood), −0.758 (holocellulose) and −0.769 (α-cellulose)). There are no significant differences in the dendroclimatic relationships of the δ13C series of different wood components. Through both stationary temporal and spatial-statistical perspectives, the moisture drivers (summer/autumn) had a significant impact on three ring width parameters and three components of Masson pine. Overall, the radial growth and the δ13C series showed different responses to the same climate drivers during the same period. Moreover, the R-squared values of the strongest climate-proxy correlation coefficients were smaller than 50% for TRW. Consequently, the δ13C series of Masson pine may be a more representative climate proxy than TRW parameters for dendroclimatology in subtropical China.

Masson pine (Pinus massoniana Lamb.) is a versatile tree that can be used for timber, pulp, resin production and ecological maintenance. Although great progress has been made in its superior family selection and rapid propagation, little is known about its molecular genetics, primarily due to a lack of genomic information or reliable molecular markers. In the current study, 70896 unigenes derived from masson pine were analyzed, and 3317 SSR loci were identified from 3064 SSR-containing sequences. The most abundant repeat type was the mono-nucleotide (1337, 40.3%), followed by tri-nucleotide (1223, 36.87%) and di-nucleotide (695, 20.95%). In total, 1807 pairs of non-redundant primers were designed after filtering unqualified SSR loci. One hundred primer pairs were randomly selected to be validated among 6 masson pine clones. Seventy-one of 100 primer pairs amplified the expected products, of which 37 polymorphic EST-SSRs were used to genotype 53 masson pine clones. A cluster analysis revealed three major clusters, and most of the same excellent trait clones were assigned into the same inferred clusters. These SSR data are valuable for the discovery of novel EST-SSR markers, and will provide an effective tool for further genetic research on masson pine, such as genetic linkage map construction, QTL mapping and marker-assisted selection. [ABSTRACT FROM AUTHOR]

In this study, the effect of silicone oil thermal modification at different treatment temperatures (150 ºC, 180 ºC and 210 ºC for 2 h and 4 h.) on the mechanical properties of masson pine (Pinus massoniana L.) wood was investigated. The density, modulus of elasticity (MOE), modulus of rupture (MOR), impact bending, compressive strength, and hardness of silicone oil thermal treated samples were evaluated and compared with those of untreated samples. Results showed the mechanical properties of masson pine wood reduces after silicone oil thermal modification. The higher the modification temperature, the lower the mechanical properties of Mason pine wood. At 210 ºC for 4 h, mechanical properties of the modified samples were two times lower than the mechanical properties of the untreated. Higher modification temperature and longer treatment time contributed to lower mechanical properties.

Masson pine (Pinus massoniana Lamb.) is an economically important conifer tree that can be widely used for timber, pulp, and resin production. However, the phosphate (Pi) deficiency in tropical and subtropical forest soils poses severe challenges for the productivity of masson pine. WRKY transcription factors (TFs) have been proven to play important roles in plant responses to biotic and abiotic stresses, including low Pi stress; however, little is known about their roles in masson pine. To understand the roles of P. massoniana WRKY (PmWRKY) in low Pi stress, 25 putative WRKY TFs with complete WRKY domain from transcriptome sequencing data were identified. Based on their conserved domains and zinc-finger motif, the P. massoniana WRKY were divided into three groups. Structural feature analysis shows that PmWRKY proteins contain WRKYGQK/GKK/GRK domains and a C2H2/C2HC-type zinc-finger structure. To putatively identify the function of PmWRKY members involved in low Pi stress, transcriptional profiles of 17 PmWRKYs in masson pine under different Pi stresses were systematically established using real-time quantitative RT-PCR analysis. Analysis demonstrates that the candidate PmWRKYs were involved in responses to Pi starvation—for example, PmWRKY11, 12, and 13 were upregulated both in P1 (Phosphorus content of 0.01 mM) and P2 (Phosphorus content of 0.06 mM) stresses. The available evidence conclusively sheds light on protein structures, evolutionary relationships, and expression patterns of WRKYs in response to low Pi stress of masson pine, which facilitates further functional identification and molecular breeding for the enhancement of low-phosphorous tolerance in this species. [ABSTRACT FROM AUTHOR]

Masson pine (Pinus massoniana) is primarily present within subtropical and tropical areas in China, and a number of these regions have a severe deficiency in inorganic phosphate (Pi). As a macronutrient, phosphorus plays a crucial role in plant development. Although several studies have documented the responses of masson pine to Pi starvation at a global level using RNA-Seq and comparative proteomic analyses, the detailed features in the roots that primarily respond to low Pi stress have not yet been studied. Our study examined the response of masson pine roots to a deficiency in Pi. Approximately 1117 unigenes were shown to respond to Pi deficiency by differential expression when analyzed using RNA-Seq. A total of 819 and 298 of these transcripts were up- and down-regulated, respectively. Several transporters including phosphate transporters (PHT1, PHO88), ABC transporters and metal transporters were identified. The ethylene response factor (ERF) was found to be the most abundant transcription factor. Analyses of these genes, including gene ontology enrichment and the KEGG pathway analysis, indicated that the metabolic processes are the most enriched under abiotic stresses, including Pi deficiency. This study provided abundant transcriptomic information to functionally dissect the response of masson pine roots to Pi deficiency. This will additionally aid to elucidate the biological regulatory mechanisms that the pines use to respond to low Pi stress. [ABSTRACT FROM AUTHOR]

An individual-tree basal area increment model was developed for masson pine based on 26276 observations of 13,138 trees in 987 sample plots from the 7th (2004), 8th (2009), and 9th (2014) Chinese National Forest Inventory in Hunan Province, South-central China. The model was built using a linear mixed-effects approach with sample plots included as random effects since the data have a hierarchical stochastic structure and biased estimates of the standard error of parameter estimates could be a consequence of applying ordinary least square (OLS) for regression. In addition, within-plot heteroscedasticity and autocorrelation were also considered. The final mixed-effects model was determined according to the Akaike information criterion (AIC), Bayesian information criterion (BIC), log-likelihood (Loglik), and the likelihoodratio test (LRT). The results revealed that initial diameter (DBH), the sum of the basal area (m2/ha) in trees with DBHs larger than the DBH of the subject tree (BAL), number of trees per hectare (NT), and elevation (EL) had a significant impact on individual-tree basal area increment. The mixed-effects model performed much better than the basic model produced using OLS. Additionally, the variance structure of the model errors was successfully modeled using the power function. However, the autocorrelation structures were not defined because there was no autocorrelation amongst the data. It is believed that the final model will contribute to the scientific management of the masson pine. [ABSTRACT FROM AUTHOR]

To investigate the biochemical and physiological responses of Masson pine (Pinus massoniana Lamb.) seedlings to lead stress, needles, stems, and roots of two-year-old seedlings were treated with 207PbCO3 for 33 d and then analyzed 1 and 7 d after the treatment was completed. Chlorophyll (Chl) b responded more sensitively than Chl a to needle Pb treatment, and the Chl content in the needles significantly decreased after Pb application to roots. The malondialdehyde and proline content remained almost unchanged, but superoxide dismutase and catalase activities increased on day 1 after all ways of Pb application. The reduced glutathione (GSH) content and GSH/oxidized glutathione ratio increased on day 1 after Pb application to stem or needles compared to the controls. At 7 d after the Pb application, the increase in dehydroascorbate (DHA) content and the decrease in the ascorbate (AsA)/DHA ratio implied a decreased antioxidant capacity of AsA. The results indicated that the antioxidants were sensitive to the Pb treatments and might be involved in the Masson pine tolerance to Pb stress.