Volatile Terpene Profiles of Needle and Phloem Tissues of Healthy and Tomicus destruens-Infested Pinus brutia Trees.

Coniferous trees produce secondary or defense chemicals, such as terpenes, against pest insects. Terpenes could serve as constitutive or induced defensive mechanisms, defending the tree from invasive herbivores. The Mediterranean pine shoot beetle Tomicus destruens colonizes stems and branches of Pinus brutia trees and even can kill mature trees during periodic outbreaks. We investigated whether terpene profiles of needle and stem of P. brutia trees differ between health and those infested by T. destruens. We selected 20 healthy and T. destruens-infested trees and analyzed the monoterpenes and sesquiterpenes of their needles and phloem. We found higher concentrations of tricyclene, camphene and p-cymene in the phloem of infested trees. Similarly, the needles of infested trees had higher concentrations of α-pinene, ß-pinene, myrcene, limonene, trans-ß-caryophyllene and α-humulene than healthy trees. These results show that the monoterpene and sesquiterpene profiles of P. brutia trees differed between healthy and infested trees, suggesting that volatile terpenes may be an important part of plant-induced responses against T. destruens.

Visualization of root extracellular traps in an ectomycorrhizal woody plant (Pinus densiflora) and their interactions with root-associated bacteria.

MAIN CONCLUSION: Extracellular traps in the primary root of Pinus densiflora contribute to root-associated bacterial colonization. Trapped rhizobacteria induce the production of reactive oxygen species in root-associated, cap-derived cells. Ectomycorrhizal (ECM) woody plants, such as members of Pinaceae and Fagaceae, can acquire resistance to biotic and abiotic stresses through the formation of mycorrhiza with ECM fungi. However, germinated tree seedlings do not have mycorrhizae and it takes several weeks for ectomycorrhizae to form on their root tips. Therefore, to confer protection during the early growth stage, bare primary roots require defense mechanisms other than mycorrhization. Here, we attempted to visualize root extracellular traps (RETs), an innate root defense mechanism, in the primary root of Pinus densiflora and investigate the interactions with root-associated bacteria isolated from ECM and fine non-mycorrhizal roots. Histological and histochemical imaging and colony-forming unit assays demonstrated that RETs in P. densiflora, mainly consisting of root-associated, cap-derived cells (AC-DCs) and large amounts of root mucilage, promote bacterial colonization in the rhizosphere, despite also having bactericidal activity via extracellular DNA. Four rhizobacterial strains retarded the mycelial growth of a pathogenic strain belonging to the Fusarium oxysporum species complex in dual culture assay. They also induced the production of reactive oxygen species (ROS) from host tree AC-DCs without being excluded from the rhizosphere of P. densiflora. Applying three Paraburkholderia strains, especially PM O-EM8 and PF T-NM22, showed significant differences in the ROS levels from the control group. These results reveal the indirect contributions of rhizobacteria to host root defense and suggest that root-associated bacteria could be a component of RETs as a first line of defense against root pathogens in the early growth stage of ECM woody plants.

Anti-Amnesia-like Effect of Pinus densiflora Extract by Improving Apoptosis and Neuroinflammation on Trimethyltin-Induced ICR Mice.

This study was conducted to investigate the anti-amnestic property of Korean red pine bark extract (KRPBE) on TMT-induced cognitive decline in ICR mice. As a result of looking at behavioral function, the consumption of KRPBE improved the spatial work ability, short-term learning, and memory ability by Y-maze, passive avoidance, and Morris water maze tests. KRPBE suppressed antioxidant system damage by assessing the SOD activity, reduced GSH content, and MDA levels in brain tissue. In addition, it had a protective effect on cholinergic and synaptic systems by regulating ACh levels, AChE activity, and protein expression levels of ChAT, AChE, SYP, and PSD-95. Also, the KRPBE ameliorated TMT-induced mitochondrial damage by regulating the ROS content, MMP, and ATP levels. Treatment with KRPBE suppressed Aß accumulation and phosphorylation of tau and reduced the expression level of BAX/BCl-2 ratio and caspase 3, improving oxidative stress-induced apoptosis. Moreover, treatment with KRPBE improved cognitive dysfunction by regulating the neuro-inflammatory protein expression levels of p-JNK, p-Akt, p-IκB-α, COX-2, and IL-1ß. Based on these results, the extract of Korean red pine bark, which is discarded as a byproduct of forestry, might be used as an eco-friendly material for functional foods or pharmaceuticals by having an anti-amnesia effect on cognitive impairment.

Abnormal shoot growth in Korean red pine as a response to microclimate changes due to urbanization in Korea.

Impacts of climate change (e.g., abnormal growth in plants, early flowering, and shifting vegetation zones) are being detected throughout the world. Urban land use and its resulting microclimates work in conjunction with the impacts of climate change. Among the principal environmental signals that modulate bud flush, only temperature has changed significantly in recent years. Throughout South Korea, abnormal shoots (usually known as lammas shoots) in Korean red pine (Pinus densiflora), which were once a rare phenomenon, have become notably more common in recent years. The phenomenon is prominent in urban site of each local area. These abnormal shoots appear at a higher frequency and grow to longer lengths in Seoul's hotter urban center than in suburban sites and showed a close positive correlation with urban density and a close negative correlation with vegetation cover expressed as NDVI. Differences in temperature among the urban center, urban edge, and suburban greenbelt were significantly correlated with land-use intensity. Korean red pines planted in urban parks at sites in urban centers showed a lower frequency of abnormal shoots, and the length of the shoots was shorter, compared with those at the other urban sites. Furthermore, the phenology of Korean red pines in an urban park with a fountain showed a spatial difference, depending upon the distance from the fountain: pine trees close to the fountain did not produce abnormal shoots, but abnormal shoot growth increased with the distance from the fountain. These results are noteworthy because they are related to the cooling effects of evapotranspiration from vegetated landscapes and evaporation from a water body. From the results of this study, we could confirm that microclimate change due to urbanization accelerates the impacts of climate change on plant phenology. Furthermore, we identified the possibility that judicious land-use planning could contribute to minimizing the adverse effects of climate change.

Genomic selection for growth characteristics in Korean red pine (Pinus densiflora Seibold & Zucc.).

Traditionally, selective breeding has been used to improve tree growth. However, traditional selection methods are time-consuming and limit annual genetic gain. Genomic selection (GS) offers an alternative to progeny testing by estimating the genotype-based breeding values of individuals based on genomic information using molecular markers. In the present study, we introduced GS to an open-pollinated breeding population of Korean red pine (Pinus densiflora), which is in high demand in South Korea, to shorten the breeding cycle. We compared the prediction accuracies of GS for growth characteristics (diameter at breast height [DBH], height, straightness, and volume) in Korean red pines under various conditions (marker set, model, and training set) and evaluated the selection efficiency of GS compared to traditional selection methods. Training the GS model to include individuals from various environments using genomic best linear unbiased prediction (GBLUP) and markers with a minor allele frequency larger than 0.05 was effective. The optimized model had an accuracy of 0.164-0.498 and a predictive ability of 0.018-0.441. The predictive ability of GBLUP against that of additive best linear unbiased prediction (ABLUP) was 0.86-5.10, and against the square root of heritability was 0.19-0.76, indicating that GS for Korean red pine was as efficient as in previous studies on forest trees. Moreover, the response to GS was higher than that to traditional selection regarding the annual genetic gain. Therefore, we conclude that the trained GS model is more effective than the traditional breeding methods for Korean red pines. We anticipate that the next generation of trees selected by GS will lay the foundation for the accelerated breeding of Korean red pine.

Soil carbon pools and fluxes following the regreening of a mining and smelting degraded landscape.

Increasing forest cover by regreening mining and smelting degraded landscapes provides an opportunity for global carbon (C) sequestration, however, the reported effects of regreening on soil C processes are mixed. One of the world's largest regreening programs is in the City of Greater Sudbury, Canada and has been ongoing since 1978. Prior to regreening, soils in the City of Greater Sudbury area were highly eroded, acidic, rich in metals, and poor in nutrients. This study used a chronosequence approach to investigate how forest soil C pools and fluxes have changed with stand age in highly "eroded" sites with minimal soil cover (n = 6) and "stable" sites covered by soil (n = 6). Encouragingly, the relationship between stand age and soil C processes (litterfall, litter decomposition, soil respiration, fine root growth) at both stable and eroded sites were comparable to observations reported for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) plantations that have not been subject to over a century of industrial impacts. There was a strong "home-field advantage" for local decomposers, where litter decomposition rates were higher using a site-specific pine litter compared with a common pine litter. Higher soil respiration at eroded sites was linked to higher soil temperature, likely because of a more open tree canopy. Forest floor C pools increased with stand age while mineral soil C and aggregate C concentrations decreased with stand age. This loss of soil C is small relative to the substantial increases in aboveground tree and forest floor C pools, leading to a sizeable increase in total ecosystem C pools following regreening.

The single and interactive effects of aluminium and low pH, or Ca/Al ratios on red pine seedlings.

Acid deposition has been one of the major environmental pollution problems for longer than 50 years, since the 1970s. Investigation on the interactive effects of aluminum (Al) and low pH or Ca/Al ratios on red pine (Pinus densiflora Sieb. and Zucc.) has been required but lacking. In the present study, needles of red pine seedlings exposed to Al treatments with solution pH 4.0 and 3.5 exhibited purplish leaf characteristics of Al toxicity. The dry weights of the needle and whole plant, and the current needle elongation were linearly reduced with Al concentrations from 0, 13 to 26 ppm. Results show that red pine is an intermediate species in sensitivity to Al and is insensitive to low pH. However, the synergistic interactions of low pH treatments with the elevated Al were significant. Al toxicity to red pine was significantly enlarged with reduced pH. The root length and whole plant length were significantly decreased at 1:10 of Ca/Al ratios (p < 0.05), but Al phytotoxicity was completely lost when the Ca/Al molar ratio was 10:1. Liming is still an applicable measure to remediate acidification problems by natural or anthropogenic factors such as acid deposition.

Pest categorisation of Coleosporium asterum, C. montanum and C. solidaginis.

The EFSA Plant Health Panel performed a pest categorisation of Coleosporium asterum (Dietel) Sydow & P. Sydow, Coleosporium montanum (Arthur & F. Kern) and Coleosporium solidaginis (Schwein.) Thüm, three basidiomycete fungi belonging to the family Coleosporiaceae, causing rust diseases on Pinus spp. (aecial hosts) and on Asteraceae (telial hosts). Coleosporium asterum was described on Aster spp. in Japan and has been reported from China, Korea, France and Portugal. Coleosporium montanum is native to North America, has been introduced to Asia and has been reported from Austria on Symphyotrichum spp. Coleosporium solidaginis has been reported on Solidago spp. from North America, Asia and Europe (Switzerland and Germany). There is a key uncertainty about these reported distributions, due to the until recently accepted synonymy between these fungi and the lack of molecular studies. The pathogens are not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072, an implementing act of Regulation (EU) 2016/2031, or in any emergency plant health legislation. There are no reports of interceptions of C. asterum, C. montanum or C. solidaginis in the EU. The pathogens can further enter into, establish in and spread within the EU via host plants for planting, other than seeds and host plant parts (e.g. cut flowers, foliage, branches), other than fruits. Entry into and spread within the EU may also occur by natural means. Host availability and climate suitability in the EU are favourable for the establishment of the pathogens in areas where host plants in the Asteraceae and Pinaceae co-exist. Impacts can be expected on both aecial and telial hosts. Phytosanitary measures are available to reduce the risk of further introduction and spread of the three pathogens in the EU. Coleosporium asterum, C. montanum and C. solidaginis satisfy the criteria that are within the remit of EFSA to assess for these species to be regarded as Union quarantine pests, but a key uncertainty exists about their EU distribution.

The Association between the Distribution of Resin Beads and the Emergence of Sirex noctilio on Red Pine in North America.

This study examined the relationships of the abundance and distribution of resin beads (signs of Sirex noctilio parent female ovipositor activity) with the abundance and distribution of emerging progeny of S. noctilio, S. nigricornis and their parasitoid Ibalia leucospoides. S. noctilio is native to Europe and is an invasive pest of pines in the Southern Hemisphere and North America; S. nigricornis is native to North America and is a secondary pest of dying pines. I. leucospoides is a parasitoid that has been widely deployed for biological control of S. noctilio. This study aimed to determine if the distribution of resin beads is associated with the height, diameter, or cardinal direction on red pines, Pinus resinosa, as well as the distribution of wood wasp and parasitoid emergence. Our results showed that among log sections taken at five heights, resin beads were most abundant on the north, east, and south sides of logs and mid log at 4.5 m above the ground. Emergence of S. noctilio was most abundant only from logs with more than five resin beads per square meter, while diameter and height were not contributing factor. None of variables evaluated (resin bead densities, height, and diameter) had significant effects on the emergence of S. nigricornis and I. leucospoides. These findings help clarify the biological significance of resin beads as indicators of S. noctilio colonization of host trees in North America.

Effects of variable retention harvesting on canopy transpiration in a red pine plantation forest.

Background: Variable Retention Harvesting (VRH) is a forest management practice applied to enhance forest growth, improve biodiversity, preserve ecosystem function and provide economic revenue from harvested timber. There are many different forms and compositions in which VRH is applied in forest ecosystems. In this study, the impacts of four different VRH treatments on transpiration were evaluated in an 83-year-old red pine (Pinus Pinus resinosa) plantation forest in the Great Lakes region in Canada. These VRH treatments included 55% aggregated crown retention (55A), 55% dispersed crown retention (55D), 33% aggregated crown retention (33A), 33% dispersed crown retention (33D) and unharvested control (CN) plot. These VRH treatments were implemented in 1-ha plots in the winter of 2014, while sap flow measurements were conducted from 2018 to 2020. Results: Study results showed that tree-level transpiration was highest among trees in the 55D treatment, followed by 33D, 55A, 33A and CN plots. We found that photosynthetically active radiation (PAR) and vapor pressure deficit (VPD) were major controls or drivers of transpiration in all VRH treatments. Our study suggests that dispersed or distributed retention of 55% basal area (55D) is the ideal forest management technique to enhance transpiration and forest growth. Conclusions: This study will help researchers, forest managers and decision-makers to improve their understanding of water cycling in forest ecosystem and adopt the best forest management regimes to enhance forest growth, health and resiliency to climate change.

UV-B and UV-C radiation trigger both common and distinctive signal perceptions and transmissions in Pinus tabuliformis Carr.

In plants, ultraviolet (UV)-light is an important driver for growth and natural distribution, and is also a valuable tool for manipulating productivity as well as biotic interactions. Understanding of plant responses to different UV radiation is sparse, especially from a systems biology perspective and particularly for conifers. Here, we evaluated the physiological and transcriptomic responses to the short-term application of high-irradiance UV-B and UV-C waves on Pinus tabuliformis Carr., a major conifer in Northern China. By undertaking time-ordered gene coexpression network analyses and network comparisons incorporating physiological traits and gene expression variation, we uncovered communalities but also differences in P. tabuliformis responses to UV-B and UV-C. Both types of spectral bands caused a significant inhibition of photosynthesis, and conversely, the improvement of antioxidant capacity, flavonoid production and signaling pathways related to stress resistance, indicating a clear switch from predominantly primary metabolism to enhanced defensive metabolism in pine. We isolated distinct subnetworks for photoreceptor-mediated signal transduction, maximum quantum efficiency of photosystem II (Fv/Fm) regulation and flavonoid biosynthesis in response to UV-B and UV-C radiation. From these subnetworks, we further identified phototropins as potentially important elements in both UV-B and UV-C signaling and, for the first time, suggesting peptide hormones to be involved in promoting flavonoid biosynthesis against UV-B, while these hormones seem not to be implicated in the defense against UV-C exposure. The present study employed an effective strategy for disentangling the complex physiological and genetic regulatory mechanisms in a nonmodel plant species, and thus, provides a suitable reference for future functional evaluations and artificial UV-light mediated growing strategies in plant production.

Korean Red Pine (Pinus densiflora) Bark Extract Attenuates Aß-Induced Cognitive Impairment by Regulating Cholinergic Dysfunction and Neuroinflammation.

In this study, we investigated the anti-amnesic effect of Korean red pine (Pinus densiflora) bark extract (KRPBE) against amyloid beta1-42 (Aß1-42)-induced neurotoxicity. We found that treatment with KRPBE improved the behavioral function in Aß-induced mice, and also boosted the antioxidant system in mice by decreasing malondialdehyde (MDA) content, increasing superoxide dismutase (SOD) activities, and reducing glutathione (GSH) levels. In addition, KRPBE improved the cholinergic system by suppressing reduced acetylcholine (ACh) content while also activating acetylcholinesterase (AChE), regulating the expression of choline acetyltransferase (ChAT), postsynaptic density protein-95 (PSD-95), and synaptophysin. KRPBE also showed an ameliorating effect on cerebral mitochondrial deficit by regulating reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and ATP levels. Moreover, KRPBE modulated the expression levels of neurotoxicity indicators Aß and phosphorylated tau (p-tau) and inflammatory cytokines TNF-α, p-IκB-α, and IL-1ß. Furthermore, we found that KRPBE improved the expression levels of neuronal apoptosis-related markers BAX and BCl-2 and increased the expression levels of BDNF and p-CREB. Therefore, this study suggests that KRPBE treatment has an anti-amnestic effect by modulating cholinergic system dysfunction and neuroinflammation in Aß1-42-induced cognitive impairment in mice.

Preclinical Study on the Hepatoprotective Effect of Pollen Extract of Pinus brutia Ten. (Red Pine) in Mice and Phenolic Acid Analysis

Objectives: Many agents, including those from herbal sources, have been sought as preventives or cures for hepatotoxicity. The pollen of Pinus brutia Ten., known as red pine (Pinaceae), is used against liver diseases in Anatolian folk medicine. Materials and Methods: In the current study, pollen ethanol extract of P. brutia was investigated for its possible hepatoprotective activity using a mouse model of CCl4-induced hepatotoxicity. Swiss albino mice were divided into five groups, and extract-treated groups were compared with a silymarin-treated group as the reference. The extract was tested at 100, 200, and 300 mg/kg (b.w.). Phenolic acids were analyzed using high-performance column chromatography (HPLC) in the extracts as pollens are usually known to be rich in phenolics. Results: Our data revealed that the extract displayed the best hepatoprotection at a dose of 100 mg/kg when compared with silymarin (Legalon®), the reference drug. HPLC analysis indicated presence of protocatechuic acid (0.176 mg/g extract), p-hydroxybenzoic acid (0.001 mg/g extract), vanillic acid (VA) (0.537 mg/g extract), syringic acid (0.050 mg/g extract), and tr-cinnamic acid (0.310 mg/g extract), while the major phenolic acid was VA. Conclusion: The outcomes of this study allow us to conclude that red pine pollen extract can serve as a promising hepatoprotective agent. Among the phenolic acids analyzed in the pollen extract, vanillic acid as the major one besides some other phenolic acids detected seems to be responsible for its remarkable hepatoprotective effect.

Antihypertensive Effects of Dehydroabietic and 4-Epi-Trans-Communic Acid Isolated from Pinus densiflora.

Korean red pine needle (RPN) exhibits various biological and pharmacological activities. Among the various compounds of RPN, we isolated dehydroabietic and 4-epi-trans-communic acid. At first, we confirmed that two compounds inhibited angiotensin converting enzyme (ACE) and induced p-Akt in human umbilical vein endothelial cells (HUVEC). RPN extract powder significantly reduced systolic blood pressure in spontaneous hypertensive rats (SHRs) through the reduced expression of ACE and angiotensin type I receptors in the lungs of SHRs. The Lineweaver-Burk plots suggested that the two compounds were noncompetitive inhibitors of ACE. Using docking analysis, we found that two compounds showed the best returned pose at ACE active sites, and formed hydrogen and hydrophobic bonds with ACE residues. These results demonstrate that RPNs may be a source of compounds effective for preventing hypertension and may be useful in the development of antihypertensive drugs.

Radial variations in xylem sap flux in a temperate red pine plantation forest.

BACKGROUND: Scaling sap flux measurements to whole-tree water use or stand-level transpiration is often done using measurements conducted at a single point in the sapwood of the tree and has the potential to cause significant errors. Previous studies have shown that much of this uncertainty is related to (i) measurement of sapwood area and (ii) variations in sap flow at different depths within the tree sapwood. RESULTS: This study measured sap flux density at three depth intervals in the sapwood of 88-year-old red pine (Pinus resinosa) trees to more accurately estimate water-use at the tree- and stand-level in a plantation forest near Lake Erie in Southern Ontario, Canada. Results showed that most of the water transport (65%) occurred in the outermost sapwood, while only 26% and 9% of water was transported in the middle and innermost depths of sapwood, respectively. CONCLUSIONS: These results suggest that failing to consider radial variations in sap flux density within trees can lead to an overestimation of transpiration by as much as 81%, which may cause large uncertainties in water budgets at the ecosystem and catchment scale. This study will help to improve our understanding of water use dynamics and reduce uncertainties in sap flow measurements in the temperate pine forest ecosystems in the Great Lakes region and help in protecting these forests in the face of climate change.

Multifaceted effects of chronic radiation exposure in Japanese red pines from Fukushima prefecture.

Despite many studies carried out to date, the long-term effects of chronic exposure on plants and animals inhabiting the territories affected by the Fukushima Dai-Ichi NPP accident remain the subject of scientific discussions. Our investigations were performed on Japanese red pine, the native tree species that is widely spread in the radioactive contaminated areas. Earlier observations revealed the radiation-induced cancellation of the apical dominance in young trees of this species. To understand the mechanism of such transformation, we evaluated the morphometric parameters of needles, the frequency of cytogenetic abnormalities, and the concentrations of the major classes of phytohormones in several natural populations of young red pine trees growing under different exposure conditions in Fukushima prefecture. No significant relationships between the morphometric parameters of needles and dose rates at the experimental sites were revealed. The frequencies of aberrant cells in the needle's intercalary meristem and the frequencies of cancellation of the apical dominance in the young pine populations in the radioactive contaminated areas were significantly higher than in the reference population. However, only cytogenetic abnormalities increased with the dose rate. We have not found the relation between the frequency of cytogenetic abnormalities in needles and cancellation of the apical dominance in the individual trees. In this paper, for the first time, it is shown that chronic radiation exposure changes the concentration ratio of the major classes of phytohormones in the needles of Japanese red pine. Given the complete lack of information about the most important regulatory system of plants in chronically irradiated populations, this study fills a substantial gap in our knowledge. Finally, our findings indicated that the most probable causes of the cancellation of apical dominance observed in chronically exposed Japanese red pines are radiation damage to the apical meristems of the trees and changes in their phytohormonal balance.

UV-B-induced molecular mechanisms of stress physiology responses in the major northern Chinese conifer Pinus tabuliformis Carr.

During their lifetimes, plants are exposed to different abiotic stress factors eliciting various physiological responses and triggering important defense processes. For UV-B radiation responses in forest trees, the genetics and molecular regulation remain to be elucidated. Here, we exposed Pinus tabuliformis Carr., a major conifer from northern China, to short-term high-intensity UV-B and employed a systems biology approach to characterize the early physiological processes and the hierarchical gene regulation, which revealed a temporal transition from primary to secondary metabolism, the buildup of enhanced antioxidant capacity and stress-signaling activation. Our findings showed that photosynthesis and biosynthesis of photosynthetic pigments were inhibited, while flavonoids and their related derivates biosynthesis, as well as glutathione and glutathione S-transferase mediated antioxidant processes, were enhanced. Likewise, stress-related phytohormones (jasmonic acid, salicylic acid and ethylene), kinase and reactive oxygen species signal transduction pathways were activated. Biological processes regulated by auxin and karrikin were, for the first time, found to be involved in plant defense against UV-B by promoting the biosynthesis of flavonoids and the improvement of antioxidant capacity in our research system. Our work evaluated the physiological and transcriptome perturbations in a conifer's response to UV-B, and generally, highlighted the necessity of a systems biology approach in addressing plant stress biology.

Antihypertensive Effects of Polyphenolic Extract from Korean Red Pine (Pinus densiflora Sieb. et Zucc.) Bark in Spontaneously Hypertensive Rats.

Korean red pine (Pinus densiflora Sieb. et Zucc.) bark is a by-product of the wood industry and contains a high level of antioxidative phenolics including flavonoids, which have a variety of beneficial health effects. This study aimed to investigate the antihypertensive effects of P. densiflora bark extract (Korean red pine bark extract; KRPBE) in spontaneously hypertensive rats (SHRs). A group of Wistar-Kyoto rats (WKRs) as a normotensive group was orally fed tap water. Four groups of SHRs were orally fed tap water, captopril (a positive control), 50 mg/kg/day of KRPBE, and 150 mg/kg/day of KRPBE, respectively. Blood pressure of rats was measured once every week for seven weeks of oral administration. After seven weeks, the lungs, kidneys, and serum were collected from rats, then angiotensin-converting enzyme (ACE) activity, angiotensin II content, and malondialdehyde (MDA) content were determined. Blood pressure of the captopril- and KRPBE-treated groups was significantly lower than that of the SHR control group. The ACE activity, angiotensin II content, and MDA content significantly decreased in the captopril- and KRPBE-treated groups than those in the SHR control group. High-performance liquid chromatography analysis revealed six phenolics in KRPBE: protocatechuic acid, procyanidin B1, catechin, caffeic acid, vanillin, and taxifolin. KRPBE, which contains plenty of antioxidative phenolics, has antihypertensive effects partly due to reduction of ACE activity and angiotensin II content, and its antioxidative effect.

Re-evaluating pattern and process to understand resilience in transitional mixed conifer forests.

A key challenge to maintaining resilient landscapes is adapting to and maintaining dynamic ecological processes. In fire-dependent ecosystems, this includes identifying and defining mechanisms through which fire influences forest structure and functionality. Interpretations of tree patterns via land survey records in the Lake States have often highlighted the importance of infrequent moderate to extreme disturbance events. However, historical survey methods are limited to observing higher severity disturbances and over large landscapes, thus it is not clear if the origin, structure, and forcing factors for either patterns or processes are adequately quantified by these methods. We used dendrochronological methods to determine how fire history and stand structure, including cohort structure, tree density, and spatial patterning, are linked within Lake States mixed conifer forests in Wisconsin. We found relatively short mean fire return intervals (MFRIs) ranging from 6 to 13 yr with little variation in fire frequency among sites. Current densities of red-pine-dominated forests are 4-37 times historical (ca. 1860) densities (mean 12×) and almost entirely spatially random, whereas historically forests were spatially aggregated at stand scales. Stands also contained multiple and/or loosely defined cohort structures suggesting very different controls operating historically than currently. Heterogeneity that helped maintain ecosystem resilience in these ecosystems historically came from frequent fire disturbance processes that affected stand-scale forest resistance. This was likely the historical dynamic across fire-adapted transitional pine forests of the Lake States.

Intra-annual dynamics of xylem growth in Pinus massoniana submitted to an experimental nitrogen addition in Central China.

In recent decades, anthropogenic activities have increased nitrogen (N) deposition in terrestrial ecosystems. This higher availability of N is expected to impact plant growth. However, the effects of N deposition on tree growth remain inconclusive due to the wide variability of experimental methods used. This study aimed to test the effect of short-term N addition on the intra-annual wood formation of Chinese red pine (Pinus massoniana Lamb.) in a warm-temperate forest of Central China. From 2013, solution containing 25 kg N ha-1 year-1 was applied monthly to the understory of experimental plots from April to December to double the current natural N deposition. Each week from March to December in 2014 and 2015, cambial activity and the timings and dynamics of xylem formation were monitored by collecting microcores from stems. Xylem formation lasted from March to November, producing an average of 19 and 33 cells for all studied trees in 2014 and 2015, respectively. No difference in xylem cell production was observed between control and N-treated trees. Moreover, N-treated trees had similar timings, rates and durations of xylem formation as control trees. These findings indicated that short-term N addition was unable to affect timings and dynamics of xylem formation in Chinese red pine of warm-temperate forest.