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1.
Int J Mol Sci ; 22(9)2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33919026

RESUMO

The role of ArabinoGalactan Proteins (AGPs) in the sexual reproduction of gymnosperms is not as well documented as that of angiosperms. In earlier studies, we demonstrated that AGPs play important roles during ovule differentiation in Larix decidua Mill. The presented results encouraged us to carry out further studies focused on the functions of these unique glycoproteins during pollen/pollen tube and ovule interactions in Larix. We identified and analyzed the localization of AGPs epitopes by JIM4, JIM8, JIM13 and LM2 antibodies (Abs) in male gametophytes and ovule tissue during pollination, the progamic phase, and after fertilization and in vitro growing pollen tubes. Our results indicated that (1) AGPs recognized by JIM4 Abs play an essential role in the interaction of male gametophytes and ovules because their appearance in ovule cells is induced by physical contact between reproductive partners; (2) after pollination, AGPs are secreted from the pollen cytoplasm into the pollen wall and contact the extracellular matrix of stigmatic tip cells followed by micropylar canal cells; (3) AGPs synthesized in nucellus cells before pollen grain germination are secreted during pollen tube growth into the extracellular matrix, where they can directly interact with male gametophytes; (4) in vitro cultured pollen tube AGPs labeled with LM2 Abs participate in the germination of pollen grain, while AGPs recognized by JIM8 Abs are essential for pollen tube tip growth.


Assuntos
Células Germinativas Vegetais/metabolismo , Larix/crescimento & desenvolvimento , Larix/metabolismo , Mucoproteínas/metabolismo , Proteínas de Plantas/metabolismo , Germinação , Tubo Polínico/crescimento & desenvolvimento , Polinização , Análise Espacial
2.
Gene ; 758: 144942, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32640309

RESUMO

WUSCHEL-related homeobox4 (WOX4) plays important roles in vascular formation and adventitious root (AR) development. Here, we cloned the WOX4 from the AR of Larix kaempferi, whose cDNA is 1452 bp in length and encodes 483 amino acids. LkWOX4 is mainly expressed in the layer formation area of the stem at 10 days after cutting and its expression levels in the middles and ends of the ARs were higher than that in the AR tips. The fused protein LkWOX4-GFP localized in the nucleus. The heterologous overexpression of LkWOX4 in 84 K poplar significantly increased AR numbers and decreased AR lengths. In LkWOX4 plants, the endogenous jasmonic acid and abscisic acid contents significantly decreased in stems, while the auxin, jasmonic acid and abscisic acid contents significantly increased in ARs. RNA-Seq of those LkWOX4 overexpression poplar plants showed that the expression of plant hormone signaling genes (ARF2, ARF3, ARF7 and ARF18), rooting-related transcription factors (WOX5, LBD29 and SCR) and root development-related genes (CYCD3, GRF1 and TAA1) were affected. Moreover, we found that LkWOX4 interacts with LkPAT18, LkACBP6, and LkCIP7 using yeast two hybrid screening. Thus, we found LkWOX4 involves in the AR initiation and development, which might be regulated through the IAA, JA and ABA signaling pathways.


Assuntos
Proteínas de Homeodomínio/genética , Larix/crescimento & desenvolvimento , Meristema/crescimento & desenvolvimento , Organogênese Vegetal/genética , Fatores de Transcrição/genética , Ácido Abscísico/metabolismo , Clonagem Molecular , Ciclopentanos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Regulação da Expressão Gênica de Plantas/genética , Ácidos Indolacéticos/metabolismo , Larix/genética , Meristema/genética , Oxilipinas/metabolismo , Transdução de Sinais/genética
3.
Sci Total Environ ; 663: 587-595, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30726767

RESUMO

Larch (Larix sp.) tree is a critical species for the future afforestation in Northeast Asia. The impacts of elevated concentrations of ground-level ozone (O3) and nitrogen (N) deposition are raising concerns. However, knowledge of the combined effects of elevated O3 and N loading are still limited. We investigated whether nitrogen loading mitigates the negative impacts of ozone on two larch species: the Japanese larch (L. kaempferi) and its hybrid larch F1 (L. gmelinii var. japonica × L. kaempferi) or not. We used open-top cambers and compared responses of the larch seedlings. Results showed the N loading mitigated the negative effects of O3 on Japanese larch. However, in hybrid larch F1, N loading did not mitigate O3-induced inhibition of growth and photosynthetic capacity. Mitigation effect of N loading on negative O3 impacts may vary between the two Larix spp., Hybrid larch F1 could be more affected by the combined effects of O3 and N loading due to its higher growth response to N loading. Elevated O3 also reduced leaf nitrogen/phosphorus (N/P) ratio by elevated O3, with significant effects in hybrid larch F1, particularly under N loading. In the present study, leaf N/P ratio was utilized to validate the hypothesis that a positive effect of N loading may be observed if O3 does not induce P limitation in Larix spp. We demonstrated a potential leaf N/P ratio function, which could reflect responses to O3 and N loading in hybrid larch F1.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Larix/efeitos dos fármacos , Nitrogênio/efeitos adversos , Ozônio/efeitos adversos , Larix/crescimento & desenvolvimento , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento
4.
Gene ; 690: 90-98, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30597235

RESUMO

The BABY BOOM2 gene, designated LkBBM2, and its promoter were isolated from hybrid larch (Larix kaempferi × L. olgensis). The open reading frame of LkBBM2 was 2574 bp, encoding 857 amino acids. The LkBBM2 protein contains two AP2 DNA binding domains and a BBM specific motif, but lacks the euANT5 motif common to AP2 family members. The LkBBM2 promoter contains several hormone response and root-specific expression elements. LkBBM2 expression was significantly higher in larch adventitious roots (ARs) than in stems, leaves or stem tips, and increased after auxin treatment. The fused protein LkBBM2-GFP was localized in both the nucleus and cytoplasm whereas LkBBM1-GFP was only localized in the nucleus. Over-expression of LkBBM2 and LkBBM1 in Arabidopsis significantly elongated the roots. Furthermore, over-expression those two genes in the hybrid poplar (Populus alba × P. glandulosa) significantly increased ARs number. We speculated that these two genes regulate AR development.


Assuntos
Núcleo Celular/metabolismo , Larix/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Arabidopsis/genética , Clonagem Molecular , Citoplasma/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Larix/genética , Larix/metabolismo , Fases de Leitura Aberta , Organogênese Vegetal , Filogenia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Populus/genética , Regiões Promotoras Genéticas , Proteínas Recombinantes/metabolismo
5.
Sci Total Environ ; 651(Pt 2): 2068-2079, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30321728

RESUMO

Microbial biomass and enzyme activity are essential for ecosystem function in managed forests; however, uncertainty remains because microbial biomass and enzymatic responses to thinning highly differ with case studies. This study addressed the drivers for the site-specific responses of microbial biomass and enzyme activity to thinning. Study sites included two oak and three larch forests; each had un-thinned control, intermediate thinning (15-23% basal area reduction), and heavy thinning treatments (30-44% basal area reduction). Soil properties (temperature, water content, pH, total and inorganic nitrogen, and total carbon/nitrogen ratio), microbial biomass, enzyme (ß-glucosidase, N-acetylglucosaminidase, leucyl aminopeptidase, acid phosphatase, and phenol oxidase) activity, and soil carbon storage were determined 6 years after thinning. Compared to the control, microbial biomass carbon and nitrogen were higher under the intermediate and the heavy thinning by 13.9 and 24.4% and 11.5 and 29.9% at one oak forests, respectively, and higher under the intermediate thinning by 53.7 and 70.7% at one larch forests. There were the post-thinning changes in leucyl aminopeptidase activity by -46.9% and by 150.0-210.0% at an oak and larch forest, respectively, acid phosphatase activity by 60.0% at one oak forest, and phenol oxidase activity by 355.0% at one oak forest. The effect sizes of thinning for soil properties explained 94% and 77% of variance of the effect sizes for microbial biomass and enzyme activity. Especially, the effect sizes for soil water content, NH4+, total carbon/nitrogen ratio, and temperature were the most influential. Furthermore, the effect size for soil carbon storage was parabolically related to the effect size for microbial biomass carbon (R2 = 0.66). These findings highlight that inconsistent thinning effects on soil properties varied microbial biomass and enzymatic responses to thinning, which differentiated the change in soil carbon storage across sites. Future studies should consider such inconsistencies when examining the effects of forest management.


Assuntos
Agricultura Florestal , Florestas , Microbiota , Microbiologia do Solo , Solo/química , Larix/crescimento & desenvolvimento , Quercus/crescimento & desenvolvimento , República da Coreia
6.
Plant Cell Environ ; 42(4): 1222-1232, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30326549

RESUMO

Conifer trees possess a typical anatomical tree-ring structure characterized by a transition from large and thin-walled earlywood tracheids to narrow and thick-walled latewood tracheids. However, little is known on how this characteristic structure is maintained across contrasting environmental conditions, due to its crucial role to ensure sap ascent and mechanical support. In this study, we monitored weekly wood cell formation for up to 7 years in two temperate conifer species (i.e., Picea abies (L.) Karst and Larix decidua Mill.) across an 8°C thermal gradient from 800 to 2,200 m a.s.l. in central Europe to investigate the impact of air temperature on rate and duration of wood cell formation. Results indicated that towards colder sites, forming tracheids compensate a decreased rate of differentiation (cell enlarging and wall thickening) by an extended duration, except for the last cells of the latewood in the wall-thickening phase. This compensation allows conifer trees to mitigate the influence of air temperature on the final tree-ring structure, with important implications for the functioning and resilience of the xylem to varying environmental conditions. The disappearing compensation in the thickening latewood cells might also explain the higher climatic sensitivity usually found in maximum latewood density.


Assuntos
Diferenciação Celular , Larix/anatomia & histologia , Picea/anatomia & histologia , Madeira/anatomia & histologia , Diferenciação Celular/fisiologia , Cinética , Larix/crescimento & desenvolvimento , Larix/fisiologia , Picea/crescimento & desenvolvimento , Picea/fisiologia , Temperatura , Madeira/citologia , Madeira/crescimento & desenvolvimento , Xilema/crescimento & desenvolvimento
7.
G3 (Bethesda) ; 9(1): 21-32, 2019 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-30333192

RESUMO

The link between phenotypic plasticity and heterosis is a broad fundamental question, with stakes in breeding. We report a case-study evaluating temporal series of wood ring traits of hybrid larch (Larix decidua × L. kaempferi and reciprocal) in relation to soil water availability. Growth rings record the tree plastic responses to past environmental conditions, and we used random regressions to estimate the reaction norms of ring width and wood density with respect to water availability. We investigated the role of phenotypic plasticity on the construction of hybrid larch heterosis and on the expression of its quantitative genetic parameters. The data came from an intra-/interspecific diallel mating design between both parental species. Progenies were grown in two environmentally contrasted sites, in France. Ring width plasticity with respect to water availability was confirmed, as all three taxa produced narrower rings under the lowest water availability. Hybrid larch appeared to be the most plastic taxon as its superiority over its parental species increased with increasing water availability. Despite the low heritabilities of the investigated traits, we found that the expression of a reliable negative correlation between them was conditional to the water availability environment. Finally, by means of a complementary simulation, we demonstrated that random regression can be applied to model the reaction norms of non-repeated records of phenotypic plasticity bound by a family structure. Random regression is a powerful tool for the modeling of reaction norms in various contexts, especially perennial species.


Assuntos
Adaptação Fisiológica/genética , Vigor Híbrido/genética , Larix/genética , Hibridização Genética , Larix/crescimento & desenvolvimento , Solo , Água , Madeira/genética , Madeira/crescimento & desenvolvimento
9.
New Phytol ; 220(2): 460-475, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30028013

RESUMO

Climate change will further constrain water availability in dry inner-alpine environments and affect water relations and growth conditions in mountain forests, including the widespread larch forests. To estimate the effects of climate conditions on water balance and growth, variation in sap flow and stem radius of European larch was measured for 3 yr along an elevation transect from 1070 to 2250 m above sea level (asl) in an inner-alpine dry valley in South Tyrol/Italy. Additionally, long-term climate-growth relations were derived from tree cores. Sap flow and radial growth were reduced in dry periods up to an elevation of 1715 m, leading to maximum annual growth at 2000 m. In a wet year no growth difference between elevations was observed. Long-term tree ring data showed a positive growth response to precipitation up to 1715 m and to temperature only above 2000 m. Our results demonstrate that reduced water availability and higher atmospheric water demand limit larch at low elevation within dry Alpine regions. This indicates a general upward shift of this species' elevational amplitude upon climate change, and respective negative effects on future silvicultural use and ecosystem services at lower elevations in the European Alps.


Assuntos
Ecossistema , Larix/crescimento & desenvolvimento , Larix/fisiologia , Transpiração Vegetal/fisiologia , Desidratação , Geografia , Itália , Microclima , Chuva , Temperatura , Fatores de Tempo , Árvores/crescimento & desenvolvimento , Árvores/fisiologia , Pressão de Vapor , Água
10.
Ying Yong Sheng Tai Xue Bao ; 29(7): 2277-2285, 2018 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-30039666

RESUMO

Based on the data of 1179 discs and whorls of 49 trees from larch (Larix olgensis) plantations located in Mengjiagang forest farm in Heilongjiang Province, China, we analyzed the longitudinal variation pattern of heartwood radius. The results showed that the heartwood radius decreased with the increases of tree height, which was basically the same as the trunk shape. The relationship between the xylem radius (XR), diameter at breast height (DBH) and cambial age (CA) with the heartwood radius was significant. The stepwise regression analysis was used to develop heartwood radius (HR) and heartwood area (HA) models: HR=b1+b2XR2+b3CA+b4XR, HA=b1+b2DBH·XR+b3CA+b4DBH·XR2. We used the evaluation statistics such as AIC, BIC, Log Likelihood and Likelihood ratio test to compare the heartwood radius and heartwood area models which fitted with the plot effect and tree effect. The heartwood radius and heartwood area models with parameters b1, b2, b3 as mixed effects performed best when the tree effect was considered. The prediction accuracy of the mixed model was better than that of the basic model. In the application, the total heartwood radius and area could be predicted by the mixed model. Beta regression model was used to simulate the heartwood proportion. In this model, all parameters were significant, and the coefficients of determination were relatively high, with a good simulation effect.


Assuntos
Larix/crescimento & desenvolvimento , China , Florestas , Análise de Regressão , Árvores
11.
Ying Yong Sheng Tai Xue Bao ; 29(7): 2382-2390, 2018 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-30039678

RESUMO

We used the correlation analysis of Larix chinensis tree-ring width chronologies, meteorological data as well as regional NDVI data to reconstruct the NDVI sequence variation of the north and south aspects of Taibai Mountain Nature Reserve in the recent 172 years. The results showed that the NDVI variation of Taibai Mountain Nature Reserve was consistent with plant growth dyna-mics. Hydrothermal condition in growing season was the dominant factor controlling NDVI changes. Tree-ring width was significantly positively correlated with NDVI in growing season. The strongest correlation occurred in July. Thus, we used the long time series of tree ring width index in July to reconstruct the regional historical period variation of NDVI sequence. The results demonstrated that historical changes of July NDVI sequence existed five dense periods and five sparse periods. Further analysis indicated that these periods corresponded with the climate change trends and drought events. The reconstructed July NDVI sequence of both northern and southern slopes of Taibai Mountain Nature Reserve highlighted the existence of quasi periodic variation of 60 years.


Assuntos
Mudança Climática , Larix/crescimento & desenvolvimento , China , Secas , Árvores
12.
Mol Genet Genomics ; 293(6): 1355-1363, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29946790

RESUMO

Somatic embryogenesis (SE) involves complex molecular signalling pathways. Understanding molecular mechanism of SE in Larix leptolepis (L. leptolepis) can aid research on genetic improvement of gymnosperms. Previously, we obtained five LaMIR166a (miR166a precursor) -overexpression embryonic cell lines in the gymnosperm Larix leptolepis. The proliferation rates of pro-embryogenic masses in transgenic and wild-type lines were calculated. Overexpression of the miR166a precursor LaMIR166a led to slower proliferation. When pro-embryogenic masses were transferred to maturation medium, the relative expression of LaMIR166a and miR166a in the LaMIR166a-overexpression lines was higher than in the wild-type during SE, while LaHDZ31-34 expression levels also increased without negative control by miR166, suggesting that regulation of HD-ZIP III by miR166a exits stage-specific characteristics. The key indole-3-acetic acid (IAA) biosynthetic gene Nitrilase of L. leptolepis (LaNIT) was identified and the effects of miR166a on auxin biosynthesis and signalling genes were studied. During SE, LaNIT, Auxin response factor1 (LaARF1) and LaARF2 mRNA levels and IAA contents were markedly higher in LaMIR166a-overexpression lines, which revealed lower deformity rate of embryos, indicating endogenous IAA synthesis is required for somatic embryo maturation in L. leptolepis. Additionally, the IAA biosynthesis and signalling genes showed similar expression patterns to LaHDZ31-34, suggesting HD-ZIP III genes have a positive regulatory effect on LaNIT. Our results suggest miR166a and LaHDZ31-34 have important roles in auxin biosynthesis and signalling during SE, which might determine if the somatic embryo normally developed to mature in L. leptolepis.


Assuntos
Ácidos Indolacéticos/metabolismo , Larix/embriologia , Larix/genética , Larix/metabolismo , RNA Mensageiro/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Larix/crescimento & desenvolvimento , Técnicas de Embriogênese Somática de Plantas , Sementes/embriologia , Sementes/genética , Sementes/metabolismo , Transdução de Sinais/genética
13.
Tree Physiol ; 38(8): 1237-1245, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29788327

RESUMO

Reconstructions of defoliation by larch bud moth (LBM, Zeiraphera diniana Gn.) based on European larch (Larix decidua Mill.) tree rings have unraveled outbreak patterns over exceptional temporal and spatial scales. In this study, we conducted tree-ring analyses on 105 increment cores of European larch from the Valais Alps, Switzerland. The well-documented history of LBM outbreaks in Valais provided a solid baseline for evaluating the LBM defoliation signal in multiple tree-ring parameters. First, we used tree-ring width measurements along with regional records of LBM outbreaks to reconstruct the occurrence of these events at two sites within the Swiss Alps. Second, we measured earlywood width, latewood width and blue intensity, and compared these parameters with tree-ring width to assess the capacity of each proxy to detect LBM defoliation. A total of six LBM outbreaks were reconstructed for the two sites between AD 1850 and 2000. Growth suppression induced by LBM was, on average, highest in latewood width (59%), followed by total ring width (54%), earlywood width (51%) and blue intensity (26%). We show that latewood width and blue intensity can improve the temporal accuracy of LBM outbreak reconstructions, as both proxies systematically detected LBM defoliation in the first year it occurred, as well as the differentiation between defoliation and non-defoliation years. This study introduces blue intensity as a promising new proxy of insect defoliation and encourages its use in conjunction with latewood width.


Assuntos
Cadeia Alimentar , Larix/crescimento & desenvolvimento , Mariposas/fisiologia , Madeira/crescimento & desenvolvimento , Animais , Comportamento Alimentar , Larix/química , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Suíça , Árvores/química , Árvores/crescimento & desenvolvimento , Madeira/química
14.
Sci Total Environ ; 621: 291-301, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29190553

RESUMO

Sewage sludge application in forest plantations is an interesting complementary alternative practice to sewage sludge reutilization and recycling, with a significant and sustainable net effect in climate change mitigation. However, to optimize it a detailed knowledge of its effects on ecosystem components such as plants, soil, water and fauna is needed. We investigated the effects of sewage sludge application on soil, tree growth and floristic diversity in a ten-year-old plantation of European larch (Larix decidua Mill.). Our one-hectare study site, located at Mélisey, Haute-Saône, France (47°753' Lat., 6°580' Long.), was subdivided into six plots. Three plots, alternating with three control plots (no sewage sludge application), were amended in June 2008 with 0.4tDWha-1 obtained from a municipal urban wastewater treatment plant in Mélisey. Within each plot, one subplot was delimited and sludge was again manually applied at 3t of DWha-1 in July 2009 and March 2010 to the soil surface of the amended subplots without incorporation. The results showed no effect on radial and height growth of European larch amended with 0.4tDWha-1. While a significant temporary increase in pH, macro-element contents (N, P and Ca) and the trace metal (Cu and Zn) concentration in the soil was observed, it had no significant effect on needles and sporocarp contents. The number of species in the amended subplots with 3tDWha-1year-1 increased by 80% compared to the control. However, the relative species abundance present only in amended subplots remains <1, except for Hypericum humifusum.


Assuntos
Fertilizantes , Larix/crescimento & desenvolvimento , Esgotos , Mudança Climática , Monitoramento Ambiental , França , Metais Pesados/análise , Solo/química , Poluentes do Solo/análise , Árvores/crescimento & desenvolvimento
15.
Tree Physiol ; 38(5): 706-720, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29194509

RESUMO

Time series of tree-ring growth show significant increases since the early 1970s at the alpine tree line, with simultaneously increasing temperatures and atmospheric CO2 concentration. For a comprehensive understanding of this growth change, the physiological response patterns at both the leaf and stem level need to be separately analyzed and identified, and can be retrieved from tree-ring growth and isotope (δ13C, δ18O) series. In this study, we assessed the relative contribution of environmental factors to interannual tree-ring variability by multivariate linear mixed-effects models and the dual isotope approach on a dataset of tree-ring records of ~400-year-old larch (Larix decidua Mill.) from a non-water-limited high-elevation site in the Swiss Alps. The models suggest that summer temperatures and the recent lack of larch budmoth outbreaks were most important for explaining growth variations and trends, while a significant direct effect of the continuously increasing CO2 concentration could not be confirmed. In contrast, δ13C and δ18O, which are strongly influenced by fractionation changes in the leaf, clearly reflected the impact of air humidity (precipitation and vapor pressure deficit) and CO2 concentration: the increase in (δ13C-derived) intrinsic water-use efficiency over the second half of the 20th century suggests an increase in carbon assimilation as a result of enhanced CO2 concentration. The tree-ring δ18O largely reflected recent precipitation as source water, thus indicating a low variability in stomatal conductance, which was confirmed by the dual isotope approach. These leaf-level effects were not reflected in stem growth as they may have been masked by the temperature-caused growth limitation controlling the allocation of increased amounts of photosynthates into wood growth. Our approach demonstrates that the identification of different roles of environmental factors on leaf and stem processes helps to improve the assessment of site-specific changes of carbon fluxes and growth performance under future environmental conditions.


Assuntos
Dióxido de Carbono/metabolismo , Larix/fisiologia , Temperatura , Larix/crescimento & desenvolvimento , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/fisiologia , Suíça
16.
PLoS One ; 12(9): e0185163, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28938020

RESUMO

Understanding how concentrations of elements and their stoichiometry change with plant growth and age is critical for predicting plant community responses to environmental change. We used long-term field experiments to explore how the leaf, stem and root carbon (C), nitrogen (N) and phosphorous (P) concentrations and their stoichiometry changed with growth and stand age in a L. principis-rupprechtii Mayr. plantation from 2012-2015 in the Qinling Mountains, China. Our results showed that the C, N and P concentrations and stoichiometric ratios in different tissues of larch stands were affected by stand age, organ type and sampling month and displayed multiple correlations with increased stand age in different growing seasons. Generally, leaf C and N concentrations were greatest in the fast-growing season, but leaf P concentrations were greatest in the early growing season. However, no clear seasonal tendencies in the stem and root C, N and P concentrations were observed with growth. In contrast to N and P, few differences were found in organ-specific C concentrations. Leaf N:P was greatest in the fast-growing season, while C:N and C:P were greatest in the late-growing season. No clear variations were observed in stem and root C:N, C:P and N:P throughout the entire growing season, but leaf N:P was less than 14, suggesting that the growth of larch stands was limited by N in our study region. Compared to global plant element concentrations and stoichiometry, the leaves of larch stands had higher C, P, C:N and C:P but lower N and N:P, and the roots had greater P and C:N but lower N, C:P and N:P. Our study provides baseline information for describing the changes in nutritional elements with plant growth, which will facilitates plantation forest management and restoration, and makes a valuable contribution to the global data pool on leaf nutrition and stoichiometry.


Assuntos
Carbono/metabolismo , Larix/metabolismo , Nitrogênio/metabolismo , Fósforo/metabolismo , Estações do Ano , Análise de Variância , Carbono/análise , China , Larix/química , Larix/crescimento & desenvolvimento , Modelos Lineares , Nitrogênio/análise , Fósforo/análise , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Caules de Planta/química , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/metabolismo , Solo/química
17.
Plant Cell Environ ; 40(9): 1972-1983, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28634999

RESUMO

Adjustment mechanisms of trees to changes in soil-water availability over long periods are poorly understood, but crucial to improve estimates of forest development in a changing climate. We compared mature trees of Scots pine (Pinus sylvestris) and European larch (Larix decidua) growing along water-permeable channels (irrigated) and under natural conditions (control) at three sites in inner-Alpine dry valleys. At two sites, the irrigation had been stopped in the 1980s. We combined measurements of basal area increment (BAI), tree height and gas-exchange physiology (Δ13 C) for the period 1970-2009. At one site, the Δ13 C of irrigated pine trees was higher than that of the control in all years, while at the other sites, it differed in pine and larch only in years with dry climatic conditions. During the first decade after the sudden change in water availability, the BAI and Δ13 C of originally irrigated pine and larch trees decreased instantly, but subsequently reached higher levels than those of the control by 2009 (15 years afterwards). We found a high plasticity in the gas-exchange physiology of pine and larch and site-specific responses to changes in water availability. Our study highlights the ability of trees to adjust to new conditions, thus showing high resilience.


Assuntos
Adaptação Fisiológica , Gases/metabolismo , Larix/fisiologia , Pinus sylvestris/fisiologia , Água/fisiologia , Irrigação Agrícola , Isótopos de Carbono , Europa (Continente) , Geografia , Larix/crescimento & desenvolvimento , Isótopos de Oxigênio , Pinus sylvestris/crescimento & desenvolvimento , Solo/química , Xilema/fisiologia
18.
Planta ; 246(3): 471-493, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28477281

RESUMO

MAIN CONCLUSION: Our findings suggest a new approach to pollen ontogenetic investigations, entailing consideration of physical factors, which enable a better understanding of exine developmental processes. The sporopollenin-containing part of the pollen wall-the exine-is one of the most complex cell walls in plants. By tracing each stage of microspore development in Larix decidua with TEM, we aimed to understand the underlying mechanisms of its exine establishment. Our hypothesis is that self-assembly interferes with exine development. Our specific aim is to generate experimental simulations of the exine developmental pattern. The sequence of events leading to exine development includes the appearance of spherical units in the periplasmic space, their rearrangement into radial columns, and the appearance of white-lined endexine lamellae. The final accumulation of sporopollenin proceeds in the post-tetrad period. The sequence of self-assembling micellar mesophases corresponds with that of the developmental events: spherical micelles; columns of spherical micelles; and laminate micelles separated by strata of water and visible as white-lined lamellae in TEM. Several patterns, simulating structures at different stages of exine development in Larix, were obtained from in vitro experiments. Purely physicochemical processes of self-assembly, which are not under direct genetic control, play an important role in exine development and share control with the genome. These findings suggest that a new approach to ontogenetic investigations, entailing consideration of physical factors (e.g., cell tensegrity), is required for a better understanding of developmental processes.


Assuntos
Parede Celular/metabolismo , Larix/crescimento & desenvolvimento , Pólen/crescimento & desenvolvimento , Parede Celular/ultraestrutura , Meiose , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Pólen/ultraestrutura
19.
Glob Chang Biol ; 23(9): 3675-3689, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28470864

RESUMO

Forest fragmentation has been found to affect biodiversity and ecosystem functioning in multiple ways. We asked whether forest size and isolation in fragmented woodlands influences the climate warming sensitivity of tree growth in the southern boreal forest of the Mongolian Larix sibirica forest steppe, a naturally fragmented woodland embedded in grassland, which is highly affected by warming, drought, and increasing anthropogenic forest destruction in recent time. We examined the influence of stand size and stand isolation on the growth performance of larch in forests of four different size classes located in a woodland-dominated forest-steppe area and small forest patches in a grassland-dominated area. We found increasing climate sensitivity and decreasing first-order autocorrelation of annual stemwood increment with decreasing stand size. Stemwood increment increased with previous year's June and August precipitation in the three smallest forest size classes, but not in the largest forests. In the grassland-dominated area, the tree growth dependence on summer rainfall was highest. Missing ring frequency has strongly increased since the 1970s in small, but not in large forests. In the grassland-dominated area, the increase was much greater than in the forest-dominated landscape. Forest regeneration decreased with decreasing stand size and was scarce or absent in the smallest forests. Our results suggest that the larch trees in small and isolated forest patches are far more susceptible to climate warming than in large continuous forests pointing to a grim future for the forests in this strongly warming region of the boreal forest that is also under high land use pressure.


Assuntos
Aquecimento Global , Larix/crescimento & desenvolvimento , Clima , Florestas , Ilhas , Árvores
20.
Environ Sci Pollut Res Int ; 24(7): 6634-6647, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28083741

RESUMO

Ozone (O3) pollution and soil infertility may negatively affect boreal forests across the Northern Hemisphere. Impacts to economically and ecologically important larches (Larix sp., Pinacaeae) are particularly concerning. Using a free air O3 enrichment (FACE) system, we investigated the effect of 2-year elevated O3 exposure (≈66 nmol mol-1) on Japanese larch (L. kaempferi) and its hybrid larch F1 (L. gmelinii var. japonica × L. kaempferi) planted directly into either fertile brown forest soil (BF) or BF mixed with infertile volcanic ash soil (VA). Overall, photosynthetic pigmentation and the growth performance of the stem and crown were reduced in both taxa exposed to elevated O3. Furthermore, hybrid larch, in both O3 treatments, performed better than Japanese larch. This finding contradicts findings of prior experiments with potential experimental artifacts of O3 exposure facilities and root restrictions. Elevated O3 also disproportionately inhibited stem diameter growth and caused an imbalance in chlorophylls a/b and chlorophyll/carotenoid ratios. Hybrid and Japanese larches grown in BF and VA had a significantly lower drop of stem diameter over the run of stem height (from base to top) when exposed to elevated O3, compared to ambient O3. This finding indicates altered stem shape under elevated O3. Among 11 response variables, there were no significant interactions between O3 treatment and taxa. There was also no significant interaction of soil condition and taxa, suggesting that the two larches shared a similar response to O3 and soil type. Understanding the performance of hybrid larch in relation to its parent species has ramifications for breeding success in a soil-degraded and O3-polluted environment.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Larix/crescimento & desenvolvimento , Ozônio/análise , Solo/química , Erupções Vulcânicas/análise , Poluentes Atmosféricos/toxicidade , Dióxido de Carbono/metabolismo , Florestas , Japão , Larix/efeitos dos fármacos , Larix/metabolismo , Ozônio/toxicidade , Fotossíntese/efeitos dos fármacos , Melhoramento Vegetal , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Caules de Planta/efeitos dos fármacos , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/metabolismo
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