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1.
Plant Sci ; 289: 110280, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31623773

RESUMO

MADS-box genes encode transcription factors involved in the control of many important developmental processes, especially the flower development of angiosperms. Analysis on gene regulatory relationship between MADS-box genes is useful for understanding the molecular mechanism of flower development. In this study, we focused on the regulatory relationship between MADS-box transcription factors APETALA1 (AP1) and PISTILLATA(PI)/DEFICIENS (DEF) in birch. We found that BpPI was an authentic target gene of BpAP1, and BpAP1 activated the expression of BpPI via directly binding to the CArG box motif. Functional analysis of BpPI showed that overexpression of BpPI may delay flowering via restricting flowering activators, in which BpAP1 was significantly down-regulated. We further investigated the regulatory of BpAP1 by BpPI, and found that BpPI could directly bind to the promoter of BpAP1 to restrict BpAP1 expression. In addition, we also found that BpPI could interact with its hypothetical partner BpDEF to co-regulate BpAP1 in birch. Our results suggested that overexpression of BpPI may delay flowering via restricting flowering activators, and there is a negative feedback loop between BpAP1 and BpPI/BpDEF heterodimer in birch. Our results will bring new evidences for further analysis of the molecular mechanism of flower formation in plants that produced unisexual flowers.


Assuntos
Betula/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/genética , Proteínas de Plantas/genética , Betula/crescimento & desenvolvimento , Flores/genética , Flores/crescimento & desenvolvimento , Hibridização Genética , Proteínas de Domínio MADS/metabolismo , Proteínas de Plantas/metabolismo
2.
Int J Mol Sci ; 20(19)2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31548512

RESUMO

The CUP-SHAPED COTYLEDON 2 (CUC2) gene, which is negatively regulated by microRNA164 (miR164), has been specifically linked to the regulation of leaf margin serration and the maintenance of phyllotaxy in model plants. However, few studies have investigated these effects in woody plants. In this study, we integrated genomic, transcriptomic, and physiology approaches to explore the function of BpCUC2 gene in Betula pendula growth and development. Our results showed that Betula pendula plants overexpressing BpCUC2, which is targeted by BpmiR164, exhibit shortened internodes and abnormal leaf shapes. Subsequent analysis indicated that the short internodes of BpCUC2 overexpressed transgenic lines and were due to decreased epidermal cell size. Moreover, transcriptome analysis, yeast one-hybrid assays, and ChIP-PCR suggested that BpCUC2 directly binds to the LTRECOREATCOR15 (CCGAC), CAREOSREP1 (CAACTC), and BIHD1OS (TGTCA) motifs of a series of IAA-related and cyclin-related genes to regulate expression. These results may be useful to our understanding of the functional role and genetic regulation of BpCUC2.


Assuntos
Betula/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Epiderme Vegetal/crescimento & desenvolvimento , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/biossíntese , Betula/genética , Epiderme Vegetal/genética , Folhas de Planta/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento
3.
Ecotoxicol Environ Saf ; 183: 109475, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442810

RESUMO

Community-scale impacts of glyphosate-based herbicides on wetland plant communities and the magnitude of those impacts that should be considered biologically relevant are poorly understood. We contrast three different thresholds for setting biologically meaningful critical effect sizes for complex ANOVA study designs. We use each of the of the critical effect sizes to determine optimal α levels for assessment of how different concentrations of glyphosate-based herbicides affect wetland plant communities over two years of herbicide application (alone and in combination with agricultural fertilizers) and two subsequent years without herbicide (or fertilizer) application. The application of glyphosate-based herbicides was found to result in a decrease in macrophyte species richness, an increase in macrophyte species evenness, a decrease in macrophyte cover and a reduction in community similarity. There was little evidence that nutrient additions directly or indirectly affected plant community endpoints. The glyphosate effects were evident in the first year of herbicide application in 2009, and became more pronounced in the second year of herbicide application in 2010. However, when herbicides were not applied in 2011, recovery was observed in most endpoints, with the exception being species evenness, for which partial recovery was not observed until 2012. Optimal α levels differed among the three critical effect sizes for each ANOVA term and endpoint combination, however regardless of differences in α levels, conclusions were generally consistent across all critical effect sizes.


Assuntos
Acer/efeitos dos fármacos , Betula/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Picea/efeitos dos fármacos , Áreas Alagadas , Acer/crescimento & desenvolvimento , Agricultura , Betula/crescimento & desenvolvimento , Glicina/toxicidade , Modelos Teóricos , Novo Brunswick , Picea/crescimento & desenvolvimento
4.
PLoS One ; 14(6): e0218884, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31226157

RESUMO

In many woody dicot plant species, colder temperatures correlate with a greater degree of leaf dissection and with larger and more abundant leaf teeth (the serrated edges along margins). The measurement of site-mean characteristics of leaf size and shape (physiognomy), including leaf dissection and tooth morphology, has been an important paleoclimate tool for over a century. These physiognomic-based climate proxies require that all woody dicot plants at a site, regardless of species, change their leaf shape rapidly and predictably in response to temperature. Here we experimentally test these assumptions by growing five woody species in growth cabinets under two temperatures (17 and 25°C). In keeping with global site-based patterns, plants tend to develop more dissected leaves with more abundant and larger leaf teeth in the cool treatment. Overall, this upholds the assumption that leaf shape responds in a particular direction to temperature change. The assumption that leaf shape variables respond to temperature in the same way regardless of species did not hold because the responses varied by species. Leaf physiognomic models for inferring paleoclimate should take into account these species-specific responses.


Assuntos
Acer/crescimento & desenvolvimento , Betula/crescimento & desenvolvimento , Betulaceae/crescimento & desenvolvimento , Folhas de Planta/anatomia & histologia , Quercus/crescimento & desenvolvimento , Acer/anatomia & histologia , Betula/anatomia & histologia , Betulaceae/anatomia & histologia , Clima , Temperatura Baixa , Temperatura Alta , Quercus/anatomia & histologia , Sementes/crescimento & desenvolvimento , Especificidade da Espécie
5.
Ying Yong Sheng Tai Xue Bao ; 30(5): 1615-1624, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31107018

RESUMO

The retrogressive succession is an important driver for dynamics of soil organic carbon (SOC) and total nitrogen (TN). We studied the quantitative distribution and synergistic accumulation characteristics of soil organic carbon and nitrogen in the primary broadleaved Korean pine (KP) forest and Betula platyphylla (BP) secondary forest in Changbai Mountain through paired plot approach. Further, we analyzed the changes of carbon pool and carbon sink effect in temperate forest soil caused by secondary succession and their carbon-nitrogen coupling mechanism. The results showed that the BP forest accumulated more organic carbon and nitrogen in the surface and subsurface soil (0-20 cm) than the KP forest, with relatively low soil C/N. Compared with KP forest, soil organic carbon storage in BP forest (0-20 cm) was higher by 14.7 t·hm-2, equivalent to a soil carbon sink gain of 29.4 g·m-2·a-1. SOC and TN concentrations were positively correlated in each soil layer of all forest types, causing a co-accumulative relationship between SOC and TN. The coefficient of determination (R2) between SOC and TN in the upper soil layers of BP forest was significantly higher than that of the KP forest, indicating that SOC accumulation under the relatively N-rich BP forest was more dependent on the accumulation of organic nitrogen. In the upper soil layers (0-10 cm) where organic matter concentrated, there was no significant difference in light fraction organic carbon and nitrogen stock between the two forest types, whereas the content, stock, and allocation percentage of heavy fraction organic carbon and nitrogen of BP forest were all significantly higher than that of the KP forest, with an average increment of 8.5 t·hm-2 in heavy fraction organic carbon stock. Those results indicated that the increase of soil organic carbon and nitrogen during secondary succession was mainly due to the increases of soil organic carbon and nitrogen pools in mineral-bound stability. The carbon-nitrogen coupling mechanisms in litter decomposition and soil organic matter formation was an important driving mechanisms underlying the changes of soil organic carbon and nitrogen pools during secondary succession.


Assuntos
Carbono/análise , Monitoramento Ambiental , Florestas , Nitrogênio/análise , Solo/química , Betula/crescimento & desenvolvimento , China , Pinus/metabolismo
6.
Tree Physiol ; 39(6): 1046-1060, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30976801

RESUMO

Flowering is a crucial process for plants that is under complex genetic control. AP1 acts as an organizer and a switch for the transition from vegetative to reproductive growth. In our previous study, we found that overexpression of BpAP1 significantly promoted the formation of male inflorescence in birch (Betula platyphlla × B. pendula). In this study, we aimed at investigating the molecular regulatory mechanism of BpAP1 during the process of male inflorescence formation in birch. We found that overexpression of BpAP1 affected the expression of many flowering-related genes, and had significant effect on B class MADS-box genes. A BpAP1-mediated gene regulatory network was constructed and B class gene BpDEF was finally predicted as a key target gene of BpAP1. Chromatin immunoprecipitation results indicated that BpAP1 could directly regulate BpDEF during the process of male inflorescence formation. Yeast one-hybrid assays and its validation in tobacco results suggested that BpAP1 regulated BpDEF via binding to a consensus DNA sequence known as CArG box. Gene function analysis of BpDEF indicated that BpDEF may function in sex-determination, and in particular specify the identity of male inflorescence in birch. Our results provide valuable clues for our understanding of the molecular mechanism of BpAP1 during the process of male inflorescence formation in birch.


Assuntos
Betula/crescimento & desenvolvimento , Betula/genética , Proteínas de Domínio MADS/genética , Proteínas de Plantas/genética , Betula/metabolismo , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Regulação da Expressão Gênica de Plantas , Hibridização Genética , Proteínas de Domínio MADS/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo
7.
Int J Mol Sci ; 20(5)2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30866467

RESUMO

MYB proteins play important roles in the regulation of plant growth, development, and stress responses. Overexpression of BplMYB46 from Betula platyphylla improved plant salt and osmotic tolerances. In the present study, the interaction of eight avian myeloblastosis viral oncogene homolog (MYB) transcription factors with BplMYB46 was investigated using the yeast two-hybrid system, which showed that BplMYB46 could form homodimers and heterodimers with BplMYB6, BplMYB8, BplMYB11, BplMYB12, and BplMYB13. Relative beta-glucuronidase activity and chromatin immunoprecipitation assays showed that the interaction between BplMYB46 and the five MYBs increased the binding of BplMYB46 to the MYBCORE motif. A subcellular localization study showed that these MYBs were all located in the nucleus. Real-time fluorescence quantitative PCR results indicated that the expressions of BplMYB46 and the five MYB genes could be induced by salt and osmotic stress, and the BplMYB46 and BplMYB13 exhibited the most similar expression patterns. BplMYB46 and BplMYB13 co-overexpression in tobacco using transient transformation technology improved tobacco's tolerance to salt and osmotic stresses compared with overexpressing BplMYB13 or BplMYB46 alone. Taken together, these results demonstrated that BplMYB46 could interact with five other MYBs to form heterodimers that activate the transcription of target genes via an enhanced binding ability to the MYBCORE motif to mediate reactive oxygen species scavenging in response to salt and osmotic stresses.


Assuntos
Betula/crescimento & desenvolvimento , Fatores de Transcrição/química , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Motivos de Aminoácidos , Betula/química , Betula/genética , Betula/metabolismo , Sítios de Ligação , Núcleo Celular/metabolismo , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Pressão Osmótica , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Multimerização Proteica , Estresse Salino , Técnicas do Sistema de Duplo-Híbrido
8.
New Phytol ; 222(4): 1816-1831, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30724367

RESUMO

Tree bark is a highly specialized array of tissues that plays important roles in plant protection and development. Bark tissues develop from two lateral meristems; the phellogen (cork cambium) produces the outermost stem-environment barrier called the periderm, while the vascular cambium contributes with phloem tissues. Although bark is diverse in terms of tissues, functions and species, it remains understudied at higher resolution. We dissected the stem of silver birch (Betula pendula) into eight major tissue types, and characterized these by a combined transcriptomics and metabolomics approach. We further analyzed the varying bark types within the Betulaceae family. The two meristems had a distinct contribution to the stem transcriptomic landscape. Furthermore, inter- and intraspecies analyses illustrated the unique molecular profile of the phellem. We identified multiple tissue-specific metabolic pathways, such as the mevalonate/betulin biosynthesis pathway, that displayed differential evolution within the Betulaceae. A detailed analysis of suberin and betulin biosynthesis pathways identified a set of underlying regulators and highlighted the important role of local, small-scale gene duplication events in the evolution of metabolic pathways. This work reveals the transcriptome and metabolic diversity among bark tissues and provides insights to its development and evolution, as well as its biotechnological applications.


Assuntos
Betula/genética , Casca de Planta/química , Casca de Planta/genética , Caules de Planta/genética , Transcriptoma/genética , Betula/crescimento & desenvolvimento , Vias Biossintéticas/genética , Câmbio/genética , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Lipídeos/química , Meristema/genética , Especificidade de Órgãos , Especificidade da Espécie , Nicho de Células-Tronco , Triterpenos/metabolismo , Madeira/genética
9.
Sci Total Environ ; 658: 1485-1499, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30678007

RESUMO

Due to the urban heat island effect, the time of plant pollination might markedly vary within the area of a city. However, existing pollen forecasts do not reflect the spatial variations in the pollen release time within a heterogeneous urban environment. The main objective of this study was to model the spatial pattern of flowering onset (and thus the moment of pollen release) in silver birch (Betula pendula Roth.) in Poznan (Western Poland) using land surface temperature (LST) data and in situ phenological observations. The onset of silver birch flowering was observed at 34 urban and rural sites (973 trees) in Poznan from 2012 to 2014. Forty-four thermal variables were retrieved from MODerate Resolution Imaging Spectroradiometer (MODIS) data. To predict the spatio-temporal distribution of B. pendula flowering onset dates in a city, the ordinary and partial least squares, support vector machine and random forest regression models were applied. The models' performance was examined by an internal repeated k-fold cross-validation and external validation with archival phenological data (2010). Birch flowering began significantly earlier in the urban sites compared to the rural sites (from -1.4 days in 2013, to -4.1 days in 2012). The maximum March LST difference between the urban and rural sites reached 2.4 °C in 2013 and 4.5 °C in 2012. The random forest model performed best at validation stage, i.e. the root mean square error between the predicted and observed onset dates was 1.461 days, and the determination coefficient was 0.829. A calibrated model for predicting the timing of flowering in a heterogeneous city area is an important step in developing a fine-scale forecasting system that can directly estimate pollen exposure in places where allergy sufferers live. Importantly, by incorporating only pre-flowering thermal data into the model, location-specific allergy forecasts can be delivered to the public before the actual flowering time.


Assuntos
Betula/fisiologia , Flores/fisiologia , Alérgenos/análise , Betula/crescimento & desenvolvimento , Flores/crescimento & desenvolvimento , Polônia , Pólen , Tecnologia de Sensoriamento Remoto , Reprodução , Estações do Ano , Sensação Térmica
10.
Physiol Plant ; 165(1): 114-122, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30367696

RESUMO

The research aim was to assess the effects of the plant hormone abscisic acid (ABA) and the growth regulator paclobutrazol (PBZ) on root system development during the in vitro culture of different birch and aspen genotypes. The studied genotypes involved two aspen (Populus tremula and Populus tremuloides × P. tremula) and two silver birch (Betula pendula) trees, with one of the birches characterized by its inability to root in vitro. For experiments, apical shoot segments were cultured on nutrient medium enriched with either ABA or PBZ. Additionally, the analysis of the endogenous hormones in shoots developed on hormone-free medium was conducted by high-performance liquid chromatography. The endogenous concentration of auxin indole-3-acetic acid was much higher in the aspens than that in the birches, while the highest concentration of ABA was found in the root-forming birch. The culturing of this birch genotype on medium enriched with ABA resulted in an increased root length and a higher number of lateral roots without any negative effect on either shoot growth or adventitious root (AR) formation, although these two processes were largely inhibited by ABA in the aspens. Meanwhile, PBZ promoted AR formation in both aspen and birch cultures but impaired secondary root formation and shoot growth in birches. These results suggest the use of ABA for the in vitro rooting of birches and PBZ for the rooting of aspens.


Assuntos
Ácido Abscísico/farmacologia , Betula/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Populus/crescimento & desenvolvimento , Técnicas de Cultura de Tecidos/métodos , Betula/citologia , Betula/efeitos dos fármacos , Betula/genética , Meios de Cultura/química , Meios de Cultura/farmacologia , Genótipo , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/crescimento & desenvolvimento , Populus/citologia , Populus/efeitos dos fármacos , Triazóis/farmacologia
11.
Tree Physiol ; 39(4): 544-555, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30517759

RESUMO

Air temperatures and precipitation are predicted to increase in the future, especially at high latitudes and particularly so during winter. In contrast to air temperatures, changes in soil temperatures are more difficult to predict, as the fate of the insulating snow cover is crucial in this respect. Soil conditions can also be affected by rain-on-snow events and warm spells during winter, resulting in freeze-thaw cycles, compacted snow, ice encasement and local flooding. These adverse conditions during winter could counteract the otherwise positive effects of climate change on forest growth and productivity. For studying the effects of different winter and snow conditions on young Downy birch (Betula pubescens Ehrh.) seedlings, we carried out a laboratory experiment with birch seedlings subjected to four different winter scenarios: snow covering the seedlings (SNOW), compressed snow and ice encasement (ICE), flooded and frozen soil (FLOOD) and no snow at all (NO SNOW). After the winter treatments we simulated a spring and early summer period of 9.5 weeks, and monitored the growth by measuring shoot and root biomass of the seedlings, and starch and soluble sugar concentrations. We also assessed the stress experienced by the seedlings by measuring leaf chlorophyll fluorescence and gas exchange. Although no difference in mortality was observed between the treatments, the seedlings in the SNOW and ICE treatments had significantly higher shoot and root biomass compared with those in the FLOOD and NO SNOW treatments. We found higher starch concentrations in roots of the seedlings in the SNOW and ICE treatments, compared with those in the FLOOD and NO SNOW treatments, although photosynthesis did not differ. Our results suggest a malfunction of carbohydrate distribution in the seedlings of the FLOOD and NO SNOW treatments, probably resulting from decreased sinks. The results underline the importance of an insulating and protecting snow cover for small tree seedlings, and that future winters with changed snow pattern might affect the growth of tree seedlings and thus possibly species composition and forest productivity.


Assuntos
Betula/fisiologia , Plântula/fisiologia , Betula/crescimento & desenvolvimento , Biomassa , Metabolismo dos Carboidratos , Mudança Climática , Congelamento , Fotossíntese , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Estações do Ano , Plântula/crescimento & desenvolvimento , Neve , Solo , Taiga , Temperatura Ambiente , Árvores
12.
Plant Sci ; 274: 294-308, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30080616

RESUMO

As a photoreceptor specifically for UV-B light, UVR8 gene plays an important role in the photomorphogenesis and developmental growth of plants. In this research, we isolated the UVR8 gene from birch, named BpUVR8 (AHY02156). BpUVR8 overexpression rescued the uvr8 mutant phenotype using functional complementation assay of BpUVR8 in Arabidopsis uvr8 mutants, which showed that the function of UVR8 is conserved between Arabidopsis and birch. The expression analysis of BpUVR8 indicated that this gene is expressed in various tissues, but its expression levels in leaves are higher than in other organs. Moreover, abiotic stress factors, such as UV-B, salinity, and abscisic acid (ABA) can induce the expression of BpUVR8 gene. Interestingly, the analysis of promoter activity indicated that BpUVR8 promoter not only has the promoting activity but can also respond to the induction of abiotic stress and ABA signal. So, we analyzed its function in ABA response via transgenic UVR8 overexpression in Arabidopsis. The BpUVR8 enhances the susceptibility to ABA, which indicates that BpUVR8 is regulated by ABA and can inhibit seed germination. The root length of 20-day-old 35S::BpUVR8/WT transgenic plants was 18% reduced as compared to the wild-type under the ABA treatment. The membrane of the BpUVR8-overexpressing in Arabidopsis thaliana was the most damaged after ABA treatment and 35S::BpUVR8/WT transgenic plant was more sensitive to ABA than the wild type. These results showed that BpUVR8 is a positive regulator in the ABA signal transduction pathway. In the presence of low dose of UV-B, the sensitivity of wild-type and 35S::BpUVR8/WT plants to ABA was reduced. Moreover, BpUVR8 regulates the expression of a subset of ABA-responsive genes, both in Arabidopsis and Betula platyphylla, under the ABA treatment. Our data provide evidence that BpUVR8 is a positive regulator in the UV-B-induced photomorphogenesis in plants. Moreover, we propose from this research that BpUVR8 might have an important role in integrating plant growth and ABA signaling pathway.


Assuntos
Ácido Abscísico/metabolismo , Betula/genética , Fotorreceptores de Plantas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais , Betula/crescimento & desenvolvimento , Betula/fisiologia , Betula/efeitos da radiação , Clonagem Molecular , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fotorreceptores de Plantas/genética , Plantas Geneticamente Modificadas , Raios Ultravioleta
13.
PLoS One ; 13(6): e0197289, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29874270

RESUMO

The alternative prey hypothesis predicts that the interaction between generalist predators and their main prey is a major driver of population dynamics of alternative prey species. In Fennoscandia, changes in climate and human land use are assumed to alter the dynamics of cyclic small rodents (main prey) and lead to increased densities and range expansion of an important generalist predator, the red fox Vulpes vulpes. In order to better understand the role of these potential changes in community structure on an alternative prey species, willow ptarmigan Lagopus lagopus, we analyzed nine years of population census data from SE Norway to investigate how community interactions affected their population dynamics. The ptarmigan populations showed no declining trend during the study period, and annual variations corresponded with marked periodic small rodent peaks and declines. Population growth and breeding success were highly correlated, and both demographic variables were influenced by an interaction between red fox and small rodents. Red foxes affected ptarmigan negatively only when small rodent abundance was low, which is in accordance with the alternative prey hypothesis. Our results confirm the important role of red fox predation in ptarmigan dynamics, and indicate that if small rodent cycles are disrupted, this may lead to decline in ptarmigan and other alternative prey species due to elevated predation pressure.


Assuntos
Mudança Climática , Cadeia Alimentar , Raposas/fisiologia , Modelos Biológicos , Roedores/fisiologia , Salix/crescimento & desenvolvimento , Animais , Betula/crescimento & desenvolvimento , Noruega , Dinâmica Populacional
14.
Tree Physiol ; 38(11): 1694-1705, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-29771393

RESUMO

A pot experiment was conducted to investigate the effects of nitrogen (N) addition (0, 20, 40 g N m-2 year-1, N0, N20, N40, respectively) on the growth, and biomass accumulation and allocation of coniferous and deciduous (Picea asperata Mast. and Betula albosinensis Burk.) seedlings under a range of soil moisture limitation (40%, 50%, 60%, 80% and 100% of field capacity, FC). At 100% FC, growth of shade-tolerant P. asperata increased with N supply, while that of shade-intolerant B. albosinensis reached a maximum at N20, declining somewhat thereafter. At 60% FC and lower moisture content, water availability limited the growth of P. asperata seedlings, while N availability became progressively limiting to growth with moisture increasing above 60% FC. The transition from principally water-limited response to N-limited response in B. albosinensis occurred at lower moisture content. For P. asperata, these patterns reflected the responses of roots, consistent with changes in root/shoot biomass. For B. albosinensis the response reflected changes in shoot dimensions and root biomass fraction, the latter decreasing with size and foliar [N]. We are not aware of another study demonstrating such differences in the shape of the growth responses of seedlings of differing potential growth rate, across a range in belowground resource supply. The responses of leaf photosynthesis (as well as photosynthetic water and N-use efficiencies) were consistent with the observed growth response of P. asperata to water and N availability, but not of B. albosinensis, suggesting that leaf area dynamics (not measured) dominated the response of this species. Betula albosinensis, a fast-growing species, has a relative narrow range of soil water and N availability for maximum growth, achieved by preferential allocation to the shoot as resources meet the requirements at moderate N and water supply. In contrast, P. asperata increases shoot biomass progressively with increasing resources up to moderate water supply, preferentially growing more roots when resources are not limiting, suggesting that its capacity to produce shoot biomass may reach a biological limit at moderate levels of resource supply.


Assuntos
Betula/metabolismo , Nitrogênio/metabolismo , Picea/metabolismo , Água/metabolismo , Betula/crescimento & desenvolvimento , Biomassa , Relação Dose-Resposta a Droga , Nitrogênio/administração & dosagem , Picea/crescimento & desenvolvimento , Solo/química
15.
Sci Total Environ ; 615: 1247-1261, 2018 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-29751430

RESUMO

Global changes occurring under different environmental conditions have changed stand competition, as well as nutrient and light availability, which has resulted in changes in productivity. Therefore, in the present study, the characteristics of tree-ring width formation of the prevailing Lithuanian tree species, Norway spruce, Scots pine and silver and downy birch, and key factors resulting in their differences during the last 36-year period were investigated at forest sites located on poor mineral oligotrophic and on nutrient-rich organic mesoeutrophic soils. The aim of the study was as follows: first, to separately detect the maximum possible seasonal effect of three groups of variables - meteorology, acidifying pollutants and surface ozone on the stem basal area increment (BAI) of the evaluated tree species; second, to assess the significance of each group of variables affecting the BAI of these tree species integrally with the remaining groups of variables. Norway spruce was found to be well adapted to recent environmental changes, which makes it one of the most favourable tree species for silviculture in the northeastern part of Europe. The rapid increases recorded in growth intensity since 1980 were attributed to the increase in air temperature, precipitation amount, nitrogen deposition during the vegetative stage and reductions in SO2 concentrations and S deposition. Scots pine demonstrated the highest level of resilience and capacity to adapt to recent global changes because its reaction to both negative and favourable environmental factors was best expressed. Silver and downy birch tree reactions to the effects of air concentrations of acidifying compounds, their deposition and surface ozone concentrations were the least expressed; however, a significant decline in growth intensity indicated that these tree species experienced a reduced resistance to recent changes in environmental conditions in the mature and over-mature age groups.


Assuntos
Monitoramento Ambiental/métodos , Florestas , Árvores/química , Adaptação Fisiológica , Poluentes Atmosféricos/análise , Betula/crescimento & desenvolvimento , Lituânia , Nitrogênio , Picea/crescimento & desenvolvimento , Pinus sylvestris/crescimento & desenvolvimento , Caules de Planta/química
16.
PLoS One ; 13(4): e0195630, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29624614

RESUMO

Worldwide tree mortality as induced by climate change presents a challenge to forest managers. To successfully manage vulnerable forests requires the capacity of regeneration to compensate for losses from tree mortality. We observed rapid regeneration and the growth release of young trees after warming-induced mortality in a David aspen-dominated (Populus davidiana) broad-leaved forest in Inner Mongolia, China, as based on individual tree measurements taken in 2012 and 2015 from a 6-ha permanent plot. Warming and drought stress killed large trees 10-15 m tall with a total number of 2881 trees during 2011-2012, and also thinned the upper crowns. David aspen recruitment increased 2 times during 2012-2015 and resulted in a high transition probability of David aspen replacing the same or other species, whereas the recruitment of Mongolian oak (Quercus mongolica) was much lower: it decreased from 2012 to 2015, indicating that rapid regeneration represented a regrowth phase for David aspen, and not succession to Mongolian oak. Further, we found that the recruitment density increased with canopy openness, thus implying that warming-induced mortality enhanced regeneration. Our results suggest that David aspen has a high regrowth ability to offset individual losses from warming-induced mortality. This important insight has implications for managing this vulnerable forest in the semi-arid region of northern China.


Assuntos
Florestas , Aquecimento Global , Árvores/fisiologia , Betula/crescimento & desenvolvimento , Betula/fisiologia , China , Modelos Biológicos , Populus/crescimento & desenvolvimento , Populus/fisiologia , Quercus/crescimento & desenvolvimento , Quercus/fisiologia , Regeneração , Árvores/crescimento & desenvolvimento
17.
Am J Bot ; 105(1): 42-49, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29532922

RESUMO

PREMISE OF THE STUDY: The growth limitation hypothesis (GLH) and carbon limitation hypothesis (CLH) are two dominant explanations for treeline formation. The GLH proposes that low temperature drives the treeline through constraining C sinks more than C sources, and it predicts that non-structural carbohydrate (NSC) levels are static or increase with elevation. Although the GLH has received strong support globally for evergreen treelines, there is still no consensus for deciduous treelines, which experience great asynchrony between supply and demand throughout the year. METHODS: We investigated growth and the growing-season C dynamics in a common deciduous species, Erman's birch (Betula ermanii), along an elevational gradient from the closed forest to the treeline on Changbai Mountain, Northeast China. Samples were collected from developing organs (leaves and twigs) and main storage organs (stems and roots) for NSC analysis. KEY RESULTS: Tree growth decreased with increasing elevation, and NSC concentrations differed significantly among elevations, organs, and sampling times. In particular, NSC levels varied slightly during the growing season in leaves, peaked in the middle of the growing season in twigs and stems, and increased continuously throughout the growing season in roots. NSCs also tended to increase or vary slightly in developing organs but decreased significantly in mature organs with increasing elevation. CONCLUSIONS: The decrease in NSCs with elevation in main storage organs indicates support for the CLH, while the increasing or static trends in new developing organs indicate support for the GLH. Our results suggest that the growth limitation theory may be less applicable to deciduous species' growth than to that of evergreen species.


Assuntos
Betula/crescimento & desenvolvimento , Betula/metabolismo , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Altitude , Metabolismo dos Carboidratos , Carbono/metabolismo , China , Estações do Ano
18.
Tree Physiol ; 38(9): 1437-1444, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29481688

RESUMO

Plant meristems were previously thought to be sterile. Today, meristem-associated shoot endophytes are mainly reported as contaminants from plant tissue cultures, the number of observed species being very low. However, the few strains characterized have the capacity for infecting host cells and affecting plant growth and development. Here we studied the communities of endophytic bacteria in the buds of mountain birch (Betula pubescens ssp. czerepanovii (N. I. Orlova) Hämet-Ahti) exposed to winter moth (Operophtera brumata L.) herbivory, to identify differences between sprouts and branches of mature birch trees. Mountain birch of the high subarctic is cyclically exposed to winter moth and produces sprouts to generate new trees as a survival mechanism. The majority (54%) of operational taxonomic units belonged to Xanthomonadaceae and Pseudomonales of Proteobacteria. Most of the observed species were classified as Xanthomonas (28%). Sprout buds had the highest diversity, containing approximately three times more species, and significantly more (43%) Pseudomonas species than the mature trees (14%). Our results demonstrate that endophytic communities of buds are richer than previously thought. We suggest that the meristem-associated endophytes should be studied further for a possible role in sprouting and aiding regeneration of trees.


Assuntos
Betula/crescimento & desenvolvimento , Betula/microbiologia , Endófitos/fisiologia , Herbivoria , Animais , Endófitos/genética , Finlândia , Sequenciamento de Nucleotídeos em Larga Escala , Meristema/crescimento & desenvolvimento , Meristema/microbiologia , Consórcios Microbianos/genética , Consórcios Microbianos/fisiologia , Mariposas , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Árvores/crescimento & desenvolvimento , Árvores/microbiologia , Xanthomonas/fisiologia
19.
Microb Ecol ; 75(2): 348-363, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28741266

RESUMO

Ectomycorrhizal (ECM) fungi can influence the establishment and performance of host species by increasing nutrient and water absorption. Therefore, understanding the response of ECM fungi to expected changes in the global climate is crucial for predicting potential changes in the composition and productivity of forests. While anthropogenic activity has, and will continue to, cause global temperature increases, few studies have investigated how increases in temperature will affect the community composition of ectomycorrhizal fungi. The effects of global warming are expected to be particularly strong at biome boundaries and in the northern latitudes. In the present study, we analyzed the effects of experimental manipulations of temperature and canopy structure (open vs. closed) on ectomycorrhizal fungi identified from roots of host seedlings through 454 pyrosequencing. The ecotonal boundary site selected for the study was between the southern boreal and temperate forests in northern Minnesota, USA, which is the southern limit range for Picea glauca and Betula papyrifera and the northern one for Pinus strobus and Quercus rubra. Manipulations that increased air and soil temperature by 1.7 and 3.4 °C above ambient temperatures, respectively, did not change ECM richness but did alter the composition of the ECM community in a manner dependent on host and canopy structure. The prediction that colonization of boreal tree species with ECM symbionts characteristic of temperate species would occur was not substantiated. Overall, only a small proportion of the ECM community appears to be strongly sensitive to warming.


Assuntos
Betula/microbiologia , Fungos/isolamento & purificação , Micorrizas/isolamento & purificação , Picea/microbiologia , Pinus/microbiologia , Betula/crescimento & desenvolvimento , Biodiversidade , Mudança Climática , Ecossistema , Florestas , Fungos/classificação , Fungos/genética , Fungos/crescimento & desenvolvimento , Especificidade de Hospedeiro , Minnesota , Micorrizas/classificação , Micorrizas/genética , Micorrizas/crescimento & desenvolvimento , Filogenia , Picea/crescimento & desenvolvimento , Pinus/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Microbiologia do Solo , Temperatura Ambiente
20.
Huan Jing Ke Xue ; 39(11): 5207-5216, 2018 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-30628246

RESUMO

A greenhouse experiment was conducted to study the potential of intercropping Arundo donax with Broussonetia papyrifera or Morus alba to remediate heavy metal-contaminated soil. The results showed that intercropping the herbaceous plant A. donax with woody plants B. papyrifera or M. alba was beneficial for plant growth on heavy metal-contaminated soil. This can effectively enhance the comprehensive enrichment capacity of heavy metals and improve soil enzyme activities. The photosynthetic pigment contents in the leaves of A. donax, B. papyrifera, and M. alba decreased along with remediation time under monoculture treatment for each plant. However, compared with 90 d cultivation, the chlorophyll-a and carotenoid contents in B. papyrifera leaves and chlorophyll-b and carotenoid contents in M. alba leaves under intercropping treatment after 270 d cultivation were only slightly changed. Furthermore, chlorophyll-a, chlorophyll-b, and carotenoid contents in M. alba leaves under intercropping treatment were significantly (P<0.05) increased by 99.1%, 177.1%, and 119.9%, respectively, compared with monoculture-treated M. alba, and the total biomass of M. alba increased significantly (P<0.05) by 26.1%. Compared with monoculture-treated A. donax, the total accumulation amounts of Pb and Zn in the shoots of combined plants was significantly (P<0.05) enhanced by 171% and 124% under intercropping treatment of A. donax with B. papyrifera. Compared with monoculture-treated M. alba and A. donax, the total accumulation amounts of As and Pb in the shoots of intercropped plants were significantly (P<0.05) enhanced by 150% and 76.5%, respectively, under intercropping treatment of A. donax with M. alba. Moreover, the fractions of As, Cd, Pb, and Zn in contaminated soil slightly changed under intercropping treatment of A. donax with B. papyrifera or M. alba, and soil urease, acid phosphatase, and total phosphatase activity was superior to part of the monoculture treatments after 270 d cultivation. The results further suggested that intercropping A. donax with B. papyrifera or M. alba could be effectively used for heavy metal-contaminated soil remediation, while simultaneously improving the biological quality in contaminated soil.


Assuntos
Biodegradação Ambiental , Metais Pesados/isolamento & purificação , Poaceae/metabolismo , Poluentes do Solo/isolamento & purificação , Betula/crescimento & desenvolvimento , Morus/crescimento & desenvolvimento , Solo
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