A transcriptome-based association study of growth, wood quality, and oleoresin traits in a slash pine breeding population.

Slash pine (Pinus elliottii Engelm.) is an important timber and resin species in the United States, China, Brazil and other countries. Understanding the genetic basis of these traits will accelerate its breeding progress. We carried out a genome-wide association study (GWAS), transcriptome-wide association study (TWAS) and weighted gene co-expression network analysis (WGCNA) for growth, wood quality, and oleoresin traits using 240 unrelated individuals from a Chinese slash pine breeding population. We developed high quality 53,229 single nucleotide polymorphisms (SNPs). Our analysis reveals three main results: (1) the Chinese breeding population can be divided into three genetic groups with a mean inbreeding coefficient of 0.137; (2) 32 SNPs significantly were associated with growth and oleoresin traits, accounting for the phenotypic variance ranging from 12.3% to 21.8% and from 10.6% to 16.7%, respectively; and (3) six genes encoding PeTLP, PeAP2/ERF, PePUP9, PeSLP, PeHSP, and PeOCT1 proteins were identified and validated by quantitative real time polymerase chain reaction for their association with growth and oleoresin traits. These results could be useful for tree breeding and functional studies in advanced slash pine breeding program.

Primary and Secondary Metabolite Profiles of Lodgepole Pine Trees Change with Elevation, but Not with Latitude.

Climate change has a large influence on plant functional and phenotypic traits including plant primary and secondary metabolites. One well-established approach to investigating the variation in plant metabolites involves studying plant populations along elevation and latitude gradients. We considered how two space-for-time climate change gradients (elevation and latitude) influence carbohydrate reserves (soluble sugars, starches) and secondary metabolites (monoterpenes, diterpene resin acids) of lodgepole pine trees in western Canada. We were particularly interested in the relationship of terpenes and carbohydrates with a wide range of tree, site, and climatic factors. We found that only elevation had a strong influence on the expression of both terpenes and carbohydrates of trees. Specifically, as elevation increased, concentrations of monoterpenes and diterpenes generally increased and soluble sugars (glucose, sucrose, total sugars) decreased. In contrast, latitude had no impact on either of terpenes or carbohydrates. Furthermore, we found a positive relationship between concentrations of starch and total terpenes and diterpenes in the elevation study; whereas neither starches nor sugars were correlated to terpenes in the latitude study. Similarly, both terpenes and carbohydrates had a much greater number of significant correlations to site characteristics such as slope, basal area index, and sand basal area, in the elevational than in the latitude study. Overall, these results support the conclusion that both biotic and abiotic factors likely drive the patterns of primary and secondary metabolite profiles of lodgepole pine along geographical gradients. Also, presence of a positive relationship between terpenes and starches suggests an interaction between primary ad secondary metabolites of lodgepole pine trees.

Using morphological attributes for the fast assessment of nutritional responses of Buddhist pine (Podocarpus macrophyllus [Thunb.] D. Don) seedlings to exponential fertilization.

Culturing slowly growing tree seedlings is a potential approach for managing the conflict between the increasing demand for ornamental stock and the decreasing area of farmlands due to urbanization. In this study, Buddhist pine (Podocarpus macrophyllus [Thunb.] D. Don) seedlings were raised in multishelves with light-emitting diode lighting in the spectrum of 17:75:8 (red:green:blue) at 190-320 µmol m-2 s-1 with controlled temperature and relative humidity at 19.5°C and 60%, respectively. Seedlings were fed by exponential fertilization (EF) (nitrogen [N]-phosphorus [P]2O5-K2O, 10-7-9) at eight rates of 0 (control), 20 (E20), 40 (E40), 60 (E60), 80 (E80), 100 (E100), 120 (E120), and 140 (E140) mg N seedling-1 for four months through 16 fertilizer applications. The nutritional responses of Buddhist pine seedlings can be identified and classified into various stages in response to increasing doses, up to and over 120 N seedling-1. Morphological traits, i.e., the green color index and leaf area (LA) obtained by digital analysis and the fine root growth, all remained constant in response to doses that induced steady nutrient loading. LA had a positive relationship with most of the nutritional parameters. A dose range between 60 and 120 mg N seedling-1 was recommended for the culture of Buddhist pine seedlings. At this range of fertilizer doses, measuring the leaf area through digital scanning can easily and rapidly indicate the inherent nutrient status of the seedlings.

Ethnobotany and Pharmacology of Pinus Species Growing Naturally in Indian Himalayas: A Plant Review.

Pinus species are amongst the most commonly used medicinal plants in Indian Northwestern Himalayas. Nearly all parts of the plant especially needles are believed to possess medicinal and clinical values in traditional systems of medicine such as Ayurvedic, Unani or Homeopathic. They are used to heal numerous diseases, including afflictions of the skin, eyes, throats and ears. Various parts of the plant including needles are rich in biologically active compounds, such as thunbergol, 3-carene, cembrene, α-pinene, quercetin, xanthone, etc. The scientific data available for the biological potential of this plant and its constituents have been found to be scanty and also does not satisfy the basis of their age-old folklore and local uses. This review focuses on a detailed analysis of ethnopharmacognosical studies on the needles of different Pinus species growing naturally in northwestern region of Indian Himalayas including investigations and findings that have come up with a concrete view of the abilities of plant components for example phenolics, flavonoids, tannins and other constituents to treat oxidative, inflammatory and microbial responses. Careful evaluation of the data presented may be helpful for the researchers to discover and evaluate the specific chemical entities responsible for the traditional medicinal uses of P. roxburghii, P.wallichiana, P. merkusii, P.kesiya and P.thunbergii.

Experimental arid land afforestation in Central Anatolia, Turkey.

The afforestation of arid lands faces many challenges, and perhaps the most important key for success is choosing one or more species that are adapted well for local environmental conditions. We explored species that would be suitable for the steppe region of Central Anatolia. Intensive site preparation included ripping the subsoil (to 80 cm) and plowing the upper soil before planting seedlings of Elaeagnus angustifolia, Robinia pseudoacacia, Fraxinus angustifolia, and Pinus nigra were used as tree species. We also tested the success of several shrub species: Amygdalus orientalis, Calligonum polygonoides, and Spartium junceum. After five growing seasons, E. angustifolia showed the highest survival, with 80% of planted seedlings remaining. For the shrubs, A. orientalis was the most successful species with a 95% survival rate. Broad-leaved trees grew a cumulative average of 34 cm in height in 5 years, whereas P. nigra seedings grew only 9 cm. The greatest height growth occurred in the shrubs, with A. orientalis gaining 40 cm in height in 5 years. Overall, E. angustifolia and A. orientalis appeared best suited for afforestation in these areas. R. pseodoacacia and F. angustifolia may also be used as alternative species.

Altered leaf functional traits by nitrogen addition in a nutrient-poor pine plantation: A consequence of decreased phosphorus availability.

This study aimed to determine how specific leaf area (SLA) and leaf dry matter content (LDMC) respond to N addition and understory vegetation removal in a 13-year-old Mongolian pine (Pinus sylvestris var. mongolica) plantation. Traits (SLA, LDMC, individual needle dry weight, N and P concentrations) of different-aged needles and their crown-average values were measured, and their relationships with soil N and P availability were examined. N addition and understory removal reduced soil Olsen-P by 15-91%. At the crown level, N addition significantly reduced foliar P concentration (by 19%) and SLA (by 8%), and elevated N concentration (by 31%), LDMC (by 10%) and individual leaf dry weight (by 14%); understory removal did not have a significant effect on all leaf traits. At the needle age level, traits of the previous year's needles responded more strongly to N addition and understory removal than the traits of current-year needles, particularly SLA and N concentration. SLA and LDMC correlated more closely with soil Olsen-P than with soil inorganic N, and LDMC correlated more closely with soil Olsen-P than SLA did. These results indicate that aggravated P limitation resulting from N addition and understory removal could constrain Mongolian pine growth through their effects on the leaf traits.

Vegetation development and nutrients supply of trees in habitats with high sulfur concentration in reclaimed former sulfur mines Jeziórko (Southern Poland).

The paper presents an assessment of vegetation (composition and cover-abundance), nutrient supply, and especially sulfur accumulation in the trees foliage (birch and pine) used in reforestation and wood small-reed (Calamagrostis epigejos (L.) Roth) appearing in succession on reclaimed areas of the former Jeziórko sulfur mine (southern Poland, Tarnobrzeg region). In researched area, three categories of vegetation cover were determined: category D-degraded and unsuccessfully reforested plots, and two categories with successful reforestation: P-pine and B-birch stands. On each category, four study plots (4-6 areas each, depends on site category) were established. Soil and vegetation samplings (current year and 2-year-old pine needles, birch leaves, and wood small-reed foliage) were collected on the subplots established in regular grid square (10 × 10 m) in each category. Basic soil properties and nutrient content in soils and vegetation were analyzed. Trees grew well in areas where neutralization and reclamation treatments were carried out properly and showed a good supply of nutrients (exception of phosphorus and nitrogen), while on category D, only herbaceous vegetation with low cover-abundance and dominated by wood small-reed were noted. Linear correlations between the soil and trees nutrients content occurred, while the correlations between the soil and wood small-reed did not occur. Wood small-reed did not display increased sulfur uptake which may indicate a strategy of blocking pollutant uptake from the soil and may be recommended as a species resistant to sulfurous soils.

[Production suitability regionalization study of Pinus massoniana].

The distribution, yield and sample information data of Pinus massoniana was obtained by document literature and sample investigation. Based on sample data from 12 provinces including 414 sample plots and environment factors in China,the distribution regionalization of P. massoniana was predicted by using Maxent and spatial analysis function of ArcGIS. The results showed that the northernmost distribution of P. massoniana was 33.5 degrees north latitude, and it mainly distributed in the southeast in China. Based on plant age, plant height, yield per plant and other growth index from 414 sample plots, combined vegetation form and other data, the growth regionalization of P. massoniana was carried out by using SPSS and related functions of ArcGIS. The results showed that Fujian, Guizhou and Guangxi had a lager distribution area of P. massoniana, meanwhile, it had a relatively higher yield of fresh pine needles. The relational model between environmental factors and shikimic acid,and procyanidin, and the total lignans was constructed by using SPSS regression analysis method. Then the spatial calculation function of ArcGIS was used tocarry out the quality regionalization of P. massoniana based on the relational model. The results showed that east of Sichuan, Guizhou, Chongqing had a good pine needles quality. Based on the distribution, growth and quality regionalization, the production suitability regionalization of P. massoniana was carried out. The results showed that the optimal planting base region mainly distributed in east of Sichuan, middle and east of Guizhou, and east of Guangxi.

Fractal Characteristics of Soil Retention Curve and Particle Size Distribution with Different Vegetation Types in Mountain Areas of Northern China.

Based on fractal theory, the fractal characteristics of soil particle size distribution (PSD) and soil water retention curve (WRC) under the five vegetation types were studied in the mountainous land of Northern China. Results showed that: (1) the fractal parameters of soil PSD and soil WRC varied greatly under each different vegetation type, with Quercus acutissima Carr. and Robina pseudoacacia Linn. mixed plantation (QRM) > Pinus thunbergii Parl. and Pistacia chinensis Bunge mixed plantation (PPM) > Pinus thunbergii Parl. (PTP) > Juglans rigia Linn. (JRL) > abandoned grassland (ABG); (2) the soil fractal dimensions of woodlands (QRM, PPM, PTP and JRL) were significantly higher than that in ABG, and mixed forests (QRM and PPM) were higher than that in pure forests (PTP and JRL); (3) the fractal dimension of soil was positively correlated with the silt and clay content but negatively correlated with the sand content; and (4) the fractal dimension of soil PSD was positively correlated with the soil WRC. These indicated that the fractal parameters of soil PSD and soil WRC could act as quantitative indices to reflect the physical properties of the soil, and could be used to describe the influences of the Return Farmland to Forests Projects on soil structure.

[Relationship between selection of Pinus massoniana families and Folium Pini].

Based on variation of Pinus massoniana families, heritablility and correlation analysis, the contents of shikimic acid and procyanidine (heritability 0.90, 0.70), dry weight of single branch (heritability 0.60) and and leaf length (heritability 0.46) were screened out as quality, yield and harvest cost traits of Folium Pini, respectively. For the different medicinal application of Folium Pini, varied methods were chosen to estimate weight and construct index equation. Weight adjustment based.on equal emphasis were used as economic weight determining method to select the best families, and the index (accuracy 0. 936 4 and heritability 0. 881 6) obtained was a little better than that obtained by equal emphasis, and much better than that by restricted index. The superior families selected with adjustment weight and equal emphasis were No. 46, 43 and 28. Partial regression were used as economic weight determining method to select the best families,and the index obtained had the highest accuracy (0.941 5) , index heritability (0. 889 9) and the genetic gain of shikimic acid content. The superior families selected with this method were No. 46, 27 and 47. No. 46 was the best families with maximal economic benefit. Our study indicated that suitable method for estimate weight and construct index equation can be applied for better accuracy of superior families selection of P. massoniana.

Development of population structure and spatial distribution patterns of a restored forest during 17-year succession (1993-2010) in Pingshuo opencast mine spoil, China.

Afforestation of native tree species is often recommended for ecological restoration in mining areas, but the understanding of the ecological processes of restored vegetation is quite limited. In order to provide insight of the ecological processes of restored vegetation, in this study, we investigate the development of the population structure and spatial distribution patterns of restored Robinia pseudoacacia (ROPS) and Pinus tabuliformis (PITA) mixed forests during the 17 years of the mine spoil period of the Pingshuo opencast mine, Shanxi Province, China. After a 17-year succession, apart from the two planted species, Ulmus pumila (ULPU), as an invasive species, settled in the plot along with a large number of small diameter at breast height (DBH) size. In total, there are 10,062 living individual plants, much more than that at the plantation (5105), and ROPS had become the dominant species with a section area with a breast height of 9.40 m(2) hm(-2) and a mean DBH of 6.72 cm, much higher than both PITA and ULPU. The DBH size classes of all the total species showed inverted J-shaped distributions, which may have been a result of the large number of small regenerated ULPU trees. The DBH size classes of both ROPS and PITA showed peak-type structures with individuals mainly gathering in the moderate DBH size class, indicating a relatively healthy DBH size class structure. Meanwhile, invasive ULPU were distributed in a clear L shape, concentrating on the small DBH size class, indicating a relatively low survival rate for adult trees. Both ROPS and PITA species survival in the plantation showed uniform and aggregated distribution at small scales and random with scales increasing. ULPU showed a strong aggregation at small scales as well as random with scales increasing. Both the population structure and spatial distribution indicated that ROPS dominates and will continue to dominate the community in the future succession, which should be continuously monitored.

Ecological impacts of long-term application of biosolids to a radiata pine plantation.

Assessment of the ecological impact of applying biosolids is important for determining both the risks and benefits. This study investigated the impact on soil physical, chemical and biological properties, tree nutrition and growth of long-term biosolids applications to a radiata pine (Pinus radiata D. Don) plantation growing on a Sandy Raw Soil in New Zealand. Biosolids were applied to the trial site every 3 years from tree age 6 to 19 years at three application rates: 0 (Control), 300 (Standard) and 600 (High) kg nitrogen (N) ha(-1), equivalent to 0, 3 and 6 Mg ha(-1) of dry biosolids, respectively. Tree nutrition status and growth have been monitored annually. Soil samples were collected 13 years after the first biosolids application to assess the soil properties and functioning. Both the Standard and High biosolids treatments significantly increased soil (0-50 cm depth) total carbon (C), N, and phosphorus (P), Olsen P and cation exchange capacity (CEC), reduced soil pH, but had no significant effects on soil (0-20 cm depth) physical properties including bulk density, total porosity and unsaturated hydraulic conductivity. The High biosolids treatment also increased concentrations of soil total cadmium (Cd), chromium (Cr), copper (Cu) and lead (Pb) at 25-50 cm depth, but these concentrations were still considered very low for a soil. Ecotoxicological assessment showed no significant adverse effects of biosolids application on either the reproduction of springtails (Folsomia candida) or substrate utilisation ability of the soil microbial community, indicating no negative ecological impact of bisolids-derived heavy metals or triclosan. This study demonstrated that repeated application of biosolids to a plantation forest on a poor sandy soil could significantly improve soil fertility, tree nutrition and pine productivity. However, the long-term fate of biosolids-derived N, P and litter-retained heavy metals needs to be further monitored in the receiving environment.

Response characteristics of soil fractal features to different land uses in typical purple soil watershed.

As a fundamental characteristic of soil physical properties, the soil Particle Size Distribution (PSD) is important in the research on soil moisture migration, solution transformation, and soil erosion. In this research, the PSD characteristics with distinct methods in different land uses are analyzed. The results show that the upper bound of the volume domain of the clay domain ranges from 5.743 µm to 5.749 µm for all land-use types. For the silt domain of purple soil, the value ranges among 286.852~286.966 µm. For all purple soil land-use types, the order of the volume domain fractal dimensions is D clayD silt(U)>D sand (U)>D sand and D silt>D silt(U)>D sand>D sand(U), respectively. As it is compared with all Dvi, the D silt has the most significant correlativity to the soil texture and organic matter in different land uses of the typical purple soil watersheds. Therefore, Dsilt will be a potential indictor for evaluating the proportion of fine particles in the PSD, as well as a key measurement in soil quality and productivity studies.

Conifer somatic embryogenesis: improvements by supplementation of medium with oxidation-reduction agents.

A major barrier to the commercialization of somatic embryogenesis technology in loblolly pine (Pinus taeda L.) is recalcitrance of some high-value crosses to initiate embryogenic tissue (ET) and continue early-stage somatic embryo growth. Developing initiation and multiplication media that resemble the seed environment has been shown to decrease this recalcitrance. Glutathione (GSH), glutathione disulfide (GSSG), ascorbic acid and dehydroascorbate analyses were performed weekly throughout the sequence of seed development for female gametophyte and zygotic embryo tissues to determine physiological concentrations. Major differences in stage-specific oxidation-reduction (redox) agents were observed. A simple bioassay was used to evaluate potential growth-promotion of natural and inorganic redox agents added to early-stage somatic embryo growth medium. Compounds showing statistically significant increases in early-stage embryo growth were then tested for the ability to increase initiation of loblolly pine. Low-cost reducing agents sodium dithionite and sodium thiosulfate increased ET initiation for loblolly pine and Douglas fir (Mirb) Franco. Germination medium supplementation with GSSG increased somatic embryo germination. Early-stage somatic embryos grown on medium with or without sodium thiosulfate did not differ in GSH or GSSG content, suggesting that sodium thiosulfate-mediated growth stimulation does not involve GSH or GSSG. We have developed information demonstrating that alteration of the redox environment in vitro can improve ET initiation, early-stage embryo development and somatic embryo germination in loblolly pine.

[Effects of simulated nitrogen deposition on growth and phosphorus efficiency of Pinus massoniana under low phosphorus stress].

Atmospheric nitrogen (N) deposition dramatically raised in recent decades, resulting in increases of soil N availability and N/P ratio, which would impact plant growth and P efficiency under low P stress. Taking breeding population of Pinus massoniana as test materials, a pot experiment was conducted to simulate two P conditions, i. e., homogeneous low P availability vs. heterogeneous low P among soil layers, in combination with two N deposition levels on growth traits and P absorption and utilization efficiency of P. massoniana. Under the homogeneous low phosphorus condition, growth traits and P efficiency of P. massoniana were not significantly improved by simulated nitrogen deposition, but significant nitrogen x family interaction effect was detected, with the biomass of family 40x44 and 71x20 being increased, 36x29 and 73x23 being decreased. Under the heterogeneous low P condition, significant N effects on the seedling height, biomass and P absorption efficiency were observed, due to promoted root length and root distribution ratio of topsoil. In addition, the effects of simulated N deposition on growth and P efficiency of P. massoniana were relevant to the N/P ratio. Under the homogeneous low P condition, the N/P ratio of P. massoniana plant was 13.8, plants exhibited a low sensitivity to simulated N deposition, root secreted APase activity was increased but the plant growth was not promoted. In comparison, the plant N/P ratio was 9.7 under the heterogeneous low P condition, and the plant growth and P efficiency were significantly promoted, while no obvious change occurred in root secreted APase activity.

The temporal transcriptomic response of Pinus massoniana seedlings to phosphorus deficiency.

BACKGROUND: Phosphorus (P) is an essential macronutrient for plant growth and development. Several genes involved in phosphorus deficiency stress have been identified in various plant species. However, a whole genome understanding of the molecular mechanisms involved in plant adaptations to low P remains elusive, and there is particularly little information on the genetic basis of these acclimations in coniferous trees. Masson pine (Pinus massoniana) is grown mainly in the tropical and subtropical regions in China, many of which are severely lacking in inorganic phosphate (Pi). In previous work, we described an elite P. massoniana genotype demonstrating a high tolerance to Pi-deficiency. METHODOLOGY/PRINCIPAL FINDINGS: To further investigate the mechanism of tolerance to low P, RNA-seq was performed to give an idea of extent of expression from the two mixed libraries, and microarray whose probes were designed based on the unigenes obtained from RNA-seq was used to elucidate the global gene expression profiles for the long-term phosphorus starvation. A total of 70,896 unigenes with lengths ranging from 201 to 20,490 bp were assembled from 112,108,862 high quality reads derived from RNA-Seq libraries. We identified 1,396 and 943 transcripts that were differentially regulated (P<0.05) under P1 (0.01 mM P) and P2 (0.06 mM P) Pi-deficiency conditions, respectively. Numerous transcripts were consistently differentially regulated under Pi deficiency stress, many of which were also up- or down-regulated in other species under the corresponding conditions, and are therefore ideal candidates for monitoring the P status of plants. The results also demonstrated the impact of different Pi starvation levels on global gene expression in Masson pine. CONCLUSIONS/SIGNIFICANCE: To our knowledge, this work provides the first insight into the molecular mechanisms involved in acclimation to long-term Pi starvation and different Pi availability levels in coniferous trees.

Nitrogen (N) deposition impacts seedling growth of Pinus massoniana via N:P ratio effects and the modulation of adaptive responses to low P (phosphorus).

BACKGROUND: In forest ecosystems with phosphorus (P) deficiency, the impact of atmospheric nitrogen (N) deposition on nutritional traits related to P uptake and P use potentially determines plant growth and vegetation productivity. METHODOLOGY/PRINCIPAL FINDINGS: Two N deposition simulations were combined with three soil P conditions (homogeneous P deficiency with evenly low P; heterogeneous P deficiency with low subsoil P and high topsoil P; high P) using four full-sib families of Masson pine (Pinus massoniana). Under homogeneous P deficiency, N had a low effect on growth due to higher N:P ratios, whereas N-sensitive genotypes had lower N:P ratios and greater N sensitivity. The N effect increased under higher P conditions due to increased P concentration and balanced N:P ratios. An N:P threshold of 12.0-15.0 was detected, and growth was increased by N with an N:P ratio ≤ 12.0 and increased by P with an N:P ratio ≥ 15.0. Under homogeneous P deficiency, increased P use efficiency by N deposition improved growth. Under heterogeneous P deficiency, a greater P deficiency under N deposition due to increased N:P ratios induced greater adaptive responses to low P (root acid phosphatase secretion and topsoil root proliferation) and improved P acquisition and growth. CONCLUSIONS/SIGNIFICANCE: N deposition diversely affected seedling growth across different P conditions and genotypes via N:P ratio effects and the modulation of adaptive responses to low P. The positive impact of N on growth was genotype-specific and increased by soil P addition due to balanced N:P ratios. These results indicate the significance of breeding N-sensitive tree genotypes and improving forest soil P status to compensate for increasing N deposition.

[Characteristics of soil microbial biomass and community composition in three types of plantations in southern subtropical area of China].

By using fumigation-extraction method and phospholipid fatty acids (PLFAs) analysis, this paper studied the characteristics of soil microbial biomass and community composition in the Erythrophleum fordii, Castanopsis hystrix, and Pinus massoniana plantations in south subtropical China. The soil microbial biomass, total PLFAs, bacterial PLFAs, and fungal PLFAs in the plantations were significantly affected by the plantation type and season, and the soil microbial biomass, total PLFAs, and individual PLFA signatures were higher in dry season than in rainy season. The C. hystrix plantation had the highest soil microbial biomass carbon and total PLFAs, while the E. fordii plantation had the highest soil microbial biomass nitrogen. There was a significant positive correlation between the soil pH and arbuscular mycorrhizal fungal (AMF) PLFA (16:1omega5c). The soil total PLFAs, gram-positive bacterial PLFAs, saprophytic fungal PLFA (18:2omega6,9c), and the ratio of gram-positive to gram-negative bacterial PLFAs were significantly positively correlated with soil organic carbon, total nitrogen, and total phosphorus, suggesting that the soil organic carbon, total nitrogen, and total phosphorus contents were the most important nutrient factors affecting the numbers and types of the soil microorganisms. In addition, the ectomycorrhizae fungal PLFA (18:1omega9c) and AMF PLFA were significantly correlated with the soil C/N ratio.

2, 6-Dichlorobenzonitrile causes multiple effects on pollen tube growth beyond altering cellulose synthesis in Pinus bungeana Zucc.

Cellulose is an important component of cell wall, yet its location and function in pollen tubes remain speculative. In this paper, we studied the role of cellulose synthesis in pollen tube elongation in Pinus bungeana Zucc. by using the specific inhibitor, 2, 6-dichlorobenzonitrile (DCB). In the presence of DCB, the growth rate and morphology of pollen tubes were distinctly changed. The organization of cytoskeleton and vesicle trafficking were also disturbed. Ultrastructure of pollen tubes treated with DCB was characterized by the loose tube wall and damaged organelles. DCB treatment induced distinct changes in tube wall components. Fluorescence labeling results showed that callose, and acidic pectin accumulated in the tip regions, whereas there was less cellulose when treated with DCB. These results were confirmed by FTIR microspectroscopic analysis. In summary, our findings showed that inhibition of cellulose synthesis by DCB affected the organization of cytoskeleton and vesicle trafficking in pollen tubes, and induced changes in the tube wall chemical composition in a dose-dependent manner. These results confirm that cellulose is involved in the establishment of growth direction of pollen tubes, and plays important role in the cell wall construction during pollen tube development despite its lower quantity.

[Carbon storage of Pinus thunbergii and Robinia pseudoacacia plantations on Nanchangshan Island, Changdao County of Shandong Province, China].

Using indigenous tree species to transform large area pure plantations has been an effective close-to-nature forest management mode in China islands. By using the biomass allometric equation and combined with the investigation data from sampling plots, the carbon storage of the dominant species Pinus thunbergii and Robinia pseudoacacia in the plantations on the Nanchangshan Island of Miaodao Archipelago in Changdao County of Shandong Province was estimated. The average carbon storage in the arbor layer of P. thunbergii and R. pseudoacacia plantations was 56.81 and 37.26 t x hm(-2), respectively, being higher than the average carbon stock (27.62 t x hm(-2)) of tree plantations in Shandong Province. Slope aspect and stand density were the important environmental and biological factors affecting the tree's carbon stock in the Island, respectively. There was no significant correlation between the average cumulative rate of biomass in the arbor layer of P. thunbergi plantation and the stand age. The P. thunbergii with good carbon sequestration function could be an ideal tree species on Nanchangshan Island.