Identification of key genes controlling monoterpene biosynthesis of Citral-type Cinnamomum bodinieri Levl. Based on transcriptome and metabolite profiling.

The citral-type is the most common chemotype in Cinnamomum bodinieri Levl (C. bodinieri), which has been widely used in the daily necessities, cosmetics, biomedicine, and aromatic areas due to their high citral content. Despite of this economic prospect, the possible gene-regulatory roles of citral biosynthesis in the same geographic environment remains unknown. In this study, the essential oils (EOs) of three citral type (B1, B2, B3) and one non-citral type (B0) varieties of C. bodinieri were identified by GC-MS after hydrodistillation extraction in July. 43 components more than 0.10% were identified in the EOs, mainly composed of monoterpenes (75.8-91.84%), and high content citral (80.63-86.33%) were identified in citral-type. Combined transcriptome and metabolite profiling analysis, plant-pathogen interaction(ko04626), MAPK signaling pathway-plant(ko04016), starch and sucrose metabolism(ko00500), plant hormone signal transduction(ko04075), terpenoid backbone biosynthesis (ko00900) and monoterpenoid biosynthesis (ko00902) pathways were enriched significantly. The gene expression of differential genes were linked to the monoterpene content, and the geraniol synthase (CbGES), alcohol dehydrogenase (CbADH), geraniol 8-hydroxylase-like (CbCYP76B6-like) and 8-hydroxygeraniol dehydrogenase (Cb10HGO) were upregulated in the citral-type, indicating that they were associated with high content of geraniol and citral. The activities of CbGES and CbADH in citral type were higher than in non-citral type, which was corroborated by enzyme-linked immunosorbent assay (ELISA). This study on the accumulation mechanism of citral provides a theoretical basis for the development of essential oil of C. bodinieri.

Fine particle trace elements at a mountain site in southern China: Source identification, transport, and health risks.

Trace elements in atmospheric particulate matter play a significant role in air quality, human health, and biogeochemical cycles. In this study, the trace elements (Ca, Al, K, Fe, Na, Mg, Zn, Pb, Mn, Ti, Cu, Cr, Sr, Ni) in PM2.5 samples collected at the summit of Mt. Lushan were analyzed to quantify their abundance, source, transport, and health risks. During the whole sampling period, the major trace elements was Ca, Al, and K. While the trace metals with the lowest concentrations were Sr, Ni, Rb, and Cd. The trace elements were influenced by air mass transport routes, exhibiting an increasing trend of crustal elements in the northwesterly airmass and anthropogenic elements (Zn, Mn, Cu, and Ni) in the easterly air masses. Construction dust, coal + biomass burning, vehicle emission, urban nitrate-rich + urban waste incineration emissions, and soil dust + industry emissions were common sources of PM2.5 on Mt. Lushan. Different air mass transport routes had various source contribution patterns. These results indicate that trace elements at Mt. Lushan are influenced by regional anthropogenic emissions and monsoon-dominated trace element transport. The total resulting cancer risk value that these elements posed were below the acceptable risk value of 1 × 10-6, while the non-carcinogenic risk value (1.72) was higher than the safety level, suggesting that non-carcinogenic effects due to these trace elements inhalation were likely to occur. Vehicle emission and coal + biomass burning were the common dominant sources of non-cancer risks posed by trace elements at Mt. Lushan.

Aquapteridospora jiangxiensis, a new aquatic hyphomycetous fungus from a freshwater habitat in China.

During an investigation of freshwater fungi in Jiangxi province, China, a new hyphomycetous fungus, Aquapteridospora jiangxiensis, was collected and isolated. Aquapteridospora jiangxiensis is characterized by its unbranched and guttulate conidiophores with multi-septa swollen at the base, polyblastic conidiogenous cells with sympodial proliferations, and denticles, and guttulate conidia with a sheath. A photo plate of the macro- and micro-morphology and a muti-loci (ITS, LSU, SSU, TEF1 and RPB2) phylogenetic tree are provided. A key to the species of Aquapteridospora is also presented in this paper.

Chemical Composition and Antioxidant Activity of the Essential Oils of Citral-Rich Chemotype Cinnamomum camphora and Cinnamomum bodinieri.

Citral chemotypes Cinnamomum camphora (C. camphora) and Cinnamomum bodinieri (C. bodinieri) are promising industrial plants that contain abundant citral. For a more in-depth study, their significant biological effect, the chemical composition and antioxidant capacity of essential oils of citral-rich chemotype C. camphora and C. bodinieri (EOCC) were determined in the present study. The EOCC yield, obtained by hydro-distillation and analyzed by gas chromatography-mass spectrometry (GC-MS), ranged from 1.45-2.64%. Forty components more than 0.1% were identified and represented, mainly by a high content of neral (28.6-39.2%), geranial (31.8-54.1%), Z-isocitral (1.8-3.2%), E-isocitral (3.2-4.7%), geraniol (1.3-2.6%) and caryophyllene (0.6-2.4%). The antioxidant properties of EOCC were estimated by DPPH, ABTS and FRAP methods. As our results indicated, the antioxidant activity was significantly correlated to oxygenated monoterpenes. The variety of C. bodinieri (N7) presented the best antioxidant profile, given its highest inhibition of DPPH radical (IC50 = 6.887 ± 0.151 mg/mL) and ABTS radical scavenging activity (IC50 = 19.08 ± 0.02 mg/mL). To the best of our knowledge, more than 88% citral of C. bodinieri was investigated and the antioxidant properties described for the first time. Considering high essential oil yield, rich citral content and high antioxidant activity, the N7 variety will be a good candidate for pharmaceutical and cosmetic development of an improved variety.

Successive mineral nitrogen or phosphorus fertilization alone significantly altered bacterial community rather than bacterial biomass in plantation soil.

Bacteria play determining roles in forest soil environment and contribute to essential functions in the cycling of nitrogen (N) and phosphorus (P). Understanding the effects of different fertilizer applications, especially successive fertilization, on soil properties and bacterial community could reveal the impacts of fertilization on forest soil ecology and shed light on the nutrient cycling in forest system. This study aimed to evaluate the impacts of successive mineral N (NH4NO3) and P (NaH2PO4) fertilization at different rates, alone or together, on soil bacterial biomass and communities at 0-5, 5-10, and 10-20 cm. Compared with the control, N fertilization decreased soil pH, but P alone or with N fertilization had negligibly negative impacts on soil pH. Different mineral fertilizer applications, alone or together, showed no significant effects on soil organic matter contents, relative to the control treatment. Bacterial biomass remained stable to different fertilizations but decreased with sampling depths. Sole N or P fertilization, rather than combined fertilizations, significantly changed soil bacterial community structures. Our results demonstrated that mineral N or P fertilization alone significantly affected bacterial community structures rather than biomass in the plantation soils. KEY POINTS: • Impacts of successive mineral fertilization on soil bacteria were determined. • Mineral fertilization showed negligible impacts on bacterial biomass. • N additions stimulated Chloroflexi relative abundances. • Mineral N or P fertilization significantly altered bacterial community structure.

Medical empirical research on forest bathing (Shinrin-yoku): a systematic review.

AIMS: This study focused on the newest evidence of the relationship between forest environmental exposure and human health and assessed the health efficacy of forest bathing on the human body as well as the methodological quality of a single study, aiming to provide scientific guidance for interdisciplinary integration of forestry and medicine. METHOD: Through PubMed, Embase, and Cochrane Library, 210 papers from January 1, 2015, to April 1, 2019, were retrieved, and the final 28 papers meeting the inclusion criteria were included in the study. RESULT: The methodological quality of papers included in the study was assessed quantitatively with the Downs and Black checklist. The methodological quality of papers using randomized controlled trials is significantly higher than that of papers using non-randomized controlled trials (p < 0.05). Papers included in the study were analyzed qualitatively. The results demonstrated that forest bathing activities might have the following merits: remarkably improving cardiovascular function, hemodynamic indexes, neuroendocrine indexes, metabolic indexes, immunity and inflammatory indexes, antioxidant indexes, and electrophysiological indexes; significantly enhancing people's emotional state, attitude, and feelings towards things, physical and psychological recovery, and adaptive behaviors; and obvious alleviation of anxiety and depression. CONCLUSION: Forest bathing activities may significantly improve people's physical and psychological health. In the future, medical empirical studies of forest bathing should reinforce basic studies and interdisciplinary exchange to enhance the methodological quality of papers while decreasing the risk of bias, thereby raising the grade of paper evidence.

What Are the Effects of Moso Bamboo Expansion into Japanese Cedar on Arbuscular Mycorrhizal Fungi: Altering the Community Composition Rather than the Diversity.

The unbridled expansion of moso bamboo (Phyllostachys edulis) occurs throughout the world and has a series of consequences. However, the effect of bamboo expansion on arbuscular mycorrhizal fungi (AMF) is still poorly understood. We assessed the changes in the AMF community during bamboo expansion into Japanese cedar (Cryptomeria japonica) forests by analyzing AMF in three forest types-Japanese cedar (JC), bamboo-cedar mixed (BC) and moso bamboo (MB)-using 454 pyrosequencing technology. We found that the AMF community composition differed significantly among forest types. The relative abundance of Glomerales decreased from 74.0% in JC to 61.8% in BC and 42.5% in MB, whereas the relative abundance of Rhizophagus increased from 24.9% in JC to 35.9% in BC and 56.7% in MB. Further analysis showed that soil characteristics explained only 19.2% of the AMF community variation among forest types. Hence, vegetation is presumably the main driver of the alteration of the AMF community. The α diversity of AMF was similar between JC and MB, although it was higher in BC. Overall, this research sheds more light on AMF community dynamics during moso bamboo expansion. Our results highlight that the consequences of bamboo expansion in monoculture forests differ from those in mixed forests.

Depression of the soil arbuscular mycorrhizal fungal community by the canopy gaps in a Japanese cedar (Cryptomeria japonica) plantation on Lushan Mountain, subtropical China.

Both canopy gaps (CG) and arbuscular mycorrhizal fungi (AMF) play key roles in seedling establishment and increasing species diversity in forests. The response of AMF to canopy gaps is poorly understood. To assess the long-term effects of canopy gaps on soil AMF community, we sampled soil from plots in a 50-year Cryptomeria japonica (L.f.) D. Don. plantation, located in Lushan Mountain, subtropical China. We analyzed the AMF community, identified through 454 pyrosequencing, in soil and edaphic characteristics. Both richness and diversity of AMF in CG decreased significantly compared to the closed canopy (CC). The differences of the AMF community composition between CG and CC was also significant. The sharp response of the AMF community appears to be largely driven by vegetation transformation. Soil nutrient content also influenced some taxa, e.g., the low availability of phosphorus increased the abundance of Acaulospora. These results demonstrated that the formation of canopy gaps can depress AMF richness and alter the AMF community, which supported the plant investment hypothesis and accentuated the vital role of AMF-plant symbioses in forest management.

Soil C-N-P pools and stoichiometry as affected by intensive management of camellia oleifera plantations.

Intensive management of C. oleifera has produced many pure C. oleifera plantations. The transmission of C. oleifera plantation will potentially affect soil C, N, and P pools as well as their stoichiometric characteristics both in top soil layer and vertical soil profile due to the intensive management. To understand changes in vertical pools and stoichiometric characteristics of soil C, N, and P as affected by intensive management of C. oleifera plantations, both mixed and pure C. oleifera plantations were studied. We conducted studies in five locations in Jiangxi, China with both pure and mixed C. oleifera plantations, to compare changes in vertical pools and stoichiometry of C, N, and P. Both C and N pools were significantly different between mixed and pure plantation types of C. oleifera. However, the ratio of C:N, C:P, and N:P was consistently higher in mixed plantations with C:P and N:P altered but C:N ratio did not change with soil depth. The intensive management significantly impact both C and N pools and the stoichiometry of C, N, and P. Intensive management of C. oleifera plantations decreased both C and N pools, especially at the depth of 30-50 cm soil layer. C. oleifera plantation alteration from mixed to pure should be considered in future forest management practice considering the substantial effects on soil element cycling and distribution along vertical soil profile.

Effects of elevated UV-B radiation and N deposition on the decomposition of coarse woody debris.

Increases in nitrogen (N) deposition and ultraviolet-B (UV-B) radiation play an important role in global climate change. Because coarse woody debris (CWD) represents a sizeable proportion of total carbon (C) pool in forest ecosystems, understanding the response of CWD decomposition to increased UV-B and N deposition become necessary for evaluating forest C storage under global climate change. In this study, we investigated the respiration of CWD (RCWD) in response to increased UV-B and N deposition over a two-year period for two tree species in subtropical Chinese forests: Cunninghamia lanceolata (Lamb.) Hook. (CL) and Cinnamomum camphora (L.) Presl (CC). We found that N and UV-B treatment, alone or in combination, significantly promoted RCWD, which was further magnified by increased temperature. Moreover, the combined treatment (UV-B + N) far exceeded the sum of the individual effects of N and UV-B treatments. Our results indicated that the three components of global climate change (increased UV-B, N deposition, and warming) worked interactively to accelerate CWD decomposition in forest ecosystems, suggesting that the biogeochemical cycling of subtropical forests could be altered greatly in the future, and this alteration must be considered in modelling the effects of global climate change.

Effects of moso bamboo (Phyllostachys edulis) invasions on soil nitrogen cycles depend on invasion stage and warming.

Plant invasions may alter soil nutrient cycling due to differences in physiological traits between the invader and species they displace as well as differences in responses to anthropogenic factors such as nitrogen deposition and warming. Moso bamboo is expanding its range rapidly around the world, displacing diverse forests. In addition, near expansion fronts where invasions are patchy, moso bamboo and other species each contribute soil inputs. Nitrogen transformations and greenhouse gas (GHG) emissions are important processes associated with nutrient availability and climate change that may be impacted by bamboo invasions. We collected soils from uninvaded, mixed, and bamboo forests to understand bamboo invasion effects on carbon and N cycling. We incubated soils with warming and N addition and measured net nitrification and N mineralization rates and GHG (CO2 and N2O) emissions. Mixed forest soils had higher pH and total N and lower total organic carbon and C/N than either uninvaded or bamboo forest soils. Bamboo forest soils had higher total carbon, dissolved organic carbon, and ammonium N but lower total and nitrate N than uninvaded forest soils. Soil GHG emissions did not vary among forest types at lower temperatures but bamboo forest soils had higher CO2 and lower N2O emissions at higher temperatures. While net N transformation rates were lower in bamboo and uninvaded forest soils, they were highest in mixed forest soils, indicating non-additive effects of bamboo invasions. This suggests that plant invasion effects on N transformations and GHG emissions with global change in forests partially invaded by bamboo are difficult to predict from only comparing uninvaded and bamboo-dominated areas.

[Effects of stand structure regulation on soil labile organic carbon in Pinus elliottii plantation].

Taking 21-year-old Pinus elliottii pure plantation as the control, effects of enrichment planting with broadleaf trees (Liquidambar fornosana) after thinning the conifer trees (P. elliottii) on soil labile organic carbon of different plantations, including 3-year-old, 6-year-old, 9-year-old P. elliottii and 21-year-old P. elliottii-L. fornosana mixed plantations, were investigated. The results showed that the contents of soil dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) significantly increased in the 6-year-old and 9-year-old plantations compared with those in the 21-year-old P. elliottii pure plantation. Soil labile organic carbon contents in the 21-year-old P. elliottii-L. fornosana mixed plantation increased significantly than those in 3-year-old, 6-year-old, 9-year-old stands, and the DOC, ROC and MBC contents increased by 113.1%, 53.3% and 54.6%, respectively, compared with those in the 21-year-old P. elliottii pure plantation. The results suggested that replanting with broadleaf trees are an effective measure to improve the soil ecological function in pure P. elliottii plantation.

[Effects of reforestation on soil chemical properties and microbial communities in a severely degraded sub-tropical red soil region].

Taking the long-term reforestation experimental base established in a severely degraded sub-tropical hilly red soil region in Taihe County of Jiangxi Province in 1991 as the object, this paper studied the changes of soil nutrients and microbial communities after 19 years reforestation of Pinus elliottii forest, Liquidambarformosana forest, and P. elliotti-L. formosana forest, with the naturally restored grassland as the control. The soil organic carbon content in the L. formosana and P. elliottii-L. formosana forests (15.16+/-3.53 and 16.42+/-0.49 g kg-1, respectively) was significantly higher than that in the control (9.30+/-1.13 g kg-1), the soil total phosphorus content was in the order of the control (0.30+/-0.02 g kg-1) > P. elliottii-L. formosana forest (0.22+/-0.04 g kg-1 ) > L. formosana forest (0.14+/-0.01 g kg-1 ), while the soil available phosphorus content was 1.66+/-0.02 mg kg-1 in L. formosana forest, 2.47+/-0. 27 mg kg- in P. elliottii-L. formosana forest, and 1. 15+/-0.71 mg kg-1 in P. elliottii forest, being significantly higher than that in the control (0.01+/-0.00 mg kg-1). The total amounts of soil microbes, the amount and percentage of soil bacteria, and the amount of inorganic and organic phosphate-solubilizing microbes in L. formosana forest and P. elliottii-L. formosana forest were all significantly higher than those in P. elliottii forest and the control, while the amount and percentage of soil fungi and the percentage of soil actinomycetes in L. formosana forest and P. elliottii-L. formosana forest were significantly lower than those in the control. The soil organic carbon content was significantly positively correlated with the percentage of soil bactera, but negatively correlated with the percentage of soil fungi and actinomycetes, while the soil available phosphorus content was significantly positively correlated with the amount of organic phosphate-solubilizing microes, but not with the amount of inorganic phosphate-solubilizing microbes. It was suggested that L. formosana forest and P. elliottii-L. formosana forest could be the recommended reforestation models in sub-tropical degraded red soil region.

[Effects of converting cultivated land into forest land on the characteristics of soil organic carbon in limestone mountain area in Ruichang, Jiangxi].

Taking the forest lands having been converted from cultivated land for 5 years in Ruichang City of Jiangxi Province as test objects, this paper studied the characteristics of soil organic carbon (SOC) under 4 different conversion models (forest-seedling integration, pure medicinal forest, bamboo-broadleaved mixed forest, and multi-species mixed forest). After the conversion from cultivated land into forestlands, the contents of SOC, microbial biomass carbon (MBC), and mineralizable carbon (PMC) in 0-20 cm soil layer increased by 24.4%, 29%, and 18.4%, respectively, compared with those under the conversion from cultivated land into wasteland (P < 0.05), which indicated that the conversion from cultivated land into forest lands significantly increased the SOC content and SOC storage. The SOC, MBC, and PMC contents in 0-10 cm soil layer were significantly higher than those in 10-20 cm soil layer (P < 0.01), and the differences between the soil layers of the four forest lands were higher than those of the wasteland. Among the 4 conversion models, forest-seedling integration had more obvious effects on SOC.

[Soil soluble organic matter, microbial biomass, and enzyme activities in forest plantations in degraded red soil region of Jiangxi Province, China].

Taking the adjacent 18-year-old pure Pinus massoniana pure forest (I), P. massoniana, Liquidamber fomosana, and Schima superba mixed forest (II), S. superba pure forest (III), L. fomosana (IV) pure forest, and natural restoration fallow land (CK) in Taihe County of Jiangxi Province as test sites, a comparative study was made on their soil soluble organic carbon (SOC) and nitrogen (SON), soil microbial biomass C (MBC) and N (MBN), and soil urease and asparaginase activities. In 0-10 cm soil layer, the pool sizes of SOC, SON, MBC, and MBN at test sites ranged in 354-1007 mg x kg(-1), 24-73 mg x kg(-1), 203-488 mg x kg(-1), and 24-65 mg x kg(-1), and the soil urease and asparaginase activities were 95-133 mg x kg(-1) x d(-1) and 58-113 mg x kg(-1) x d(-1), respectively. There were significant differences in the pool sizes of SOC, SON, MBC, and MBN and the asparaginase activity among the test sites, but no significant difference was observed in the urease activity. The pool sizes of SOC and SON were in the order of IV > CK > III > I > II, those of MBC and MBN were in the order of CK > IV > III > I > II, and asparaginase activity followed the order of IV > CK > III > II > I. With the increase of soil depth, the pool sizes of SOC, SON, MBC, and MBN and the activities of soil asparaginase and urease decreased. In 0-20 cm soil layer, the SOC, SON, MBC, MBN, total C, and total N were highly correlated with each other, soil asparaginase activity was highly correlated with SOC, SON, TSN, total C, total N, MBC, and MBN, and soil urease activity was highly correlated with SON, TSN, total C, MBC and MBN.

[Relationships of soil moisture content with precipitation and evaporation in rehabilitated forests in degraded limestone red-soil region of Jiangxi Province].

By using time series analysis, the relationships of 0-40 cm soil moisture content with precipitation and evaporation in four main rehabilitated forests in degraded limestone red-soil region of Xiushui County, Jiangxi Province were studied. The results showed that in the four rehabilitated forests, the previous month's soil moisture content had stronger effects on the current month's soil moisture content in 0-40 cm and 20-40 cm layers, but had lesser effects on that in 0-10 cm layer. The soil moisture content in 20-40 cm layer was mainly affected by current month's precipitation, while that in 0-10 cm layer was mainly affected by current month's evaporation. The correlation coefficient between current month's precipitation and soil moisture content was the largest in pure Liquidambar formosana plantation, and the auto-interrelation coefficient of soil moisture content was larger in mixed forests than in pure L. formosana plantation.

[Fine-root character and its action mechanism of forest at its initial reestablished stage on degraded red soil].

This paper studied the fine-root character and its action mechanism of forest reestablished by different models for 10 years on a seriously degraded red soil, and analyzed their correlation with soil property. The results showed that fine-roots mostly distributed in 0-20 cm soil layer, accounted for 73.39% -87.41% of those in 0-40 cm soil layer. There were notable differences in nutrient storage of fine-roots under different reestablishment models. The fine- roots of medium density pure Pinus serotina forest had a much higher storage of total nitrogen, phosphorus and potassium, with the content of total nitrogen, phosphorus, potassium, calcium and magnesium being 84.47, 5.55, 38.42, 17.00 and 10.76 kg hm(-2), respectively. Soil organic matter, total nitrogen, available nitrogen, available potassium and pH had significant correlations with fine-root biomass (P < 0.05). The effects of fine-roots on soil physical properties mainly reflected on soil capillary porosity and total porosity. Fine-roots obviously increased the contents of > 0.25 mm and > 5 mm soil waterstable aggregates, and improved soil structure-stability. The correlations between fine-roots and soil bacteria and microbial quantities were significant.