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1.
Int J Mol Sci ; 22(16)2021 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-34445207

RESUMO

Recent studies show a crucial role of post-transcriptional processes in the regulation of gene expression. Our research has shown that mRNA retention in the nucleus plays a significant role in such regulation. We studied larch microsporocytes during meiotic prophase, characterized by pulsatile transcriptional activity. After each pulse, the transcriptional activity is silenced, but the transcripts synthesized at this time are not exported immediately to the cytoplasm but are retained in the cell nucleus and especially in Cajal bodies, where non-fully-spliced transcripts with retained introns are accumulated. Analysis of the transcriptome of these cells and detailed analysis of the nuclear retention and transport dynamics of several mRNAs revealed two main patterns of nuclear accumulation and transport. The majority of studied transcripts followed the first one, consisting of a more extended retention period and slow release to the cytoplasm. We have shown this in detail for the pre-mRNA and mRNA encoding RNA pol II subunit 10. In this pre-mRNA, a second (retained) intron is posttranscriptionally spliced at a precisely defined time. Fully mature mRNA is then released into the cytoplasm, where the RNA pol II complexes are produced. These proteins are necessary for transcription in the next pulse to occur.mRNAs encoding translation factors and SERRATE followed the second pattern, in which the retention period was shorter and transcripts were rapidly transferred to the cytoplasm. The presence of such a mechanism in various cell types from a diverse range of organisms suggests that it is an evolutionarily conserved mechanism of gene regulation.


Assuntos
Núcleo Celular/metabolismo , Larix/metabolismo , Pólen/metabolismo , Prófase , RNA Mensageiro/metabolismo , RNA de Plantas/metabolismo , Núcleo Celular/genética , Larix/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pólen/genética , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , RNA Mensageiro/genética , RNA de Plantas/genética
2.
Tree Physiol ; 41(10): 1918-1937, 2021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-33847364

RESUMO

Dormancy release and reactivation of temperate-zone trees involve the temperature-modulated expression of cell-cycle genes. However, information on the detailed regulatory mechanism is limited. Here, we compared the transcriptomes of the stems of active and dormant larch trees, emphasizing the expression patterns of cell-cycle genes and transcription factors and assessed their relationships and responses to temperatures. Twelve cell-cycle genes and 31 transcription factors were strongly expressed in the active stage. Promoter analysis suggested that these 12 genes might be regulated by transcription factors from 10 families. Altogether, 73 cases of regulation between 16 transcription factors and 12 cell-cycle genes were predicted, while the regulatory interactions between LaMYB20 and LaCYCB1;1, and LaRAV1 and LaCDKB1;3 were confirmed by yeast one-hybrid and dual-luciferase assays. Last, we found that LaRAV1 and LaCDKB1;3 had almost the same expression patterns during dormancy release and reactivation induced naturally or artificially by temperature, indicating that the LaRAV1-LaCDKB1;3 module functions in the temperature-modulated dormancy release and reactivation of larch trees. These results provide new insights into the link between temperature and cell-cycle gene expression, helping to understand the temperature control of tree growth and development in the context of climate change.


Assuntos
Regulação da Expressão Gênica de Plantas , Larix , Larix/metabolismo , Dormência de Plantas , Temperatura , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transcriptoma
3.
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
4.
Sci Rep ; 10(1): 22324, 2020 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-33339837

RESUMO

Microbial community and diversity in the rhizosphere is strongly influenced by biotic and/or abiotic factors, like root exudates, nutrient availability, edaphon and climate. Here we report on the microbial diversity within the rhizosphere of Larix decidua, a dominant tree species in the Alps, as compared with the microbiome within the surrounding soil. We describe how increased light intensity influenced the rhizobiome and put emphasize on methane cycling microorganisms. Microbial taxa were classified into 26 bacterial, 4 archaeal and 6 fungal phyla revealing significant differences between bulk and rhizosphere soils. The dominant prokaryotic phyla were Proteobacteria, Acidobacteria, Actinobacteria (both, rhizosphere and bulk soil) and Bacteroidetes (rhizosphere soil only) and dominant fungal phyla in both fractions included Ascomycota and Basidiomycota. The rhizosphere community was indicated by Suillus sp., plant growth-promoting bacteria and Candidatus Saccharibacteria. Predicted genes in membrane transport and carbohydrate metabolism were significantly more abundant in rhizosphere soils while genes connected with energy metabolisms and cell motility increased in bulk soils. Dominant methanotrophic microorganisms were Upland Soil Cluster (USC) α methanotrophs, Methylogaea spp. and Methylosinus spp., while most methanogens belonged to Methanomassiliicoccales. The overall abundance of methanotrophs distinctly increased in the rhizosphere but to a very different species-specific extent. The increased light intensity only led to minor changes in the rhizobiome, nevertheless a couple of indicator species (e.g. Pseudomonas sp.) for intensified light conditions were established.


Assuntos
Larix/genética , Metano/metabolismo , Microbiota/genética , Rizosfera , Archaea/genética , Archaea/isolamento & purificação , Ascomicetos/genética , Ascomicetos/isolamento & purificação , Larix/metabolismo , Larix/microbiologia , Luz , Raízes de Plantas/genética , Raízes de Plantas/microbiologia , Proteobactérias/genética , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Microbiologia do Solo
5.
Plant J ; 103(3): 1155-1173, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32369637

RESUMO

In recent years, research has increasingly focused on the key role of post-transcriptional regulation of messenger ribonucleoprotein (mRNP) function and turnover. As a result of the complexity and dynamic nature of mRNPs, the full composition of a single mRNP complex remains unrevealed and mRNPs are poorly described in plants. Here we identify canonical Sm proteins as part of the cytoplasmic mRNP complex, indicating their function in the post-transcriptional regulation of gene expression in plants. Sm proteins comprise an evolutionarily ancient family of small RNA-binding proteins involved in pre-mRNA splicing. The latest research indicates that Sm could also impact on mRNA at subsequent stages of its life cycle. In this work we show that in the microsporocyte cytoplasm of Larix decidua, the European larch, Sm proteins accumulate within distinct cytoplasmic bodies, also containing polyadenylated RNA. To date, several types of cytoplasmic bodies involved in the post-transcriptional regulation of gene expression have been described, mainly in animal cells. Their role and molecular composition in plants remain less well established, however. A total of 222 mRNA transcripts have been identified as cytoplasmic partners for Sm proteins. The specific colocalization of these mRNAs with Sm proteins within cytoplasmic bodies has been confirmed via microscopic analysis. The results from this work support the hypothesis, that evolutionarily conserved Sm proteins have been adapted to perform a whole repertoire of functions related to the post-transcriptional regulation of gene expression in Eukaryota. This adaptation presumably enabled them to coordinate the interdependent processes of splicing element assembly, mRNA maturation and processing, and mRNA translation regulation, and its degradation.


Assuntos
Proteínas de Plantas/metabolismo , RNA de Plantas/metabolismo , RNA Citoplasmático Pequeno/metabolismo , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteínas/metabolismo , Spliceossomos/metabolismo , Citoplasma/metabolismo , Regulação da Expressão Gênica de Plantas , Larix/metabolismo , RNA Mensageiro/metabolismo
6.
BMC Plant Biol ; 19(1): 247, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31185902

RESUMO

BACKGROUND: MiRNAs (microRNA) are 18-24 nt endogenous noncoding RNAs that regulate gene expression at the post-transcriptional level, including tissue-specific, developmental timing and evolutionary conservation gene expression. RESULTS: This study used high-throughput sequencing technology for the first time in Larix olgensis, predicted 78 miRNAs, including 12,229,003 reads sRNA, screened differentially expressed miRNAs. Predicting target genes was helpful for understanding the miRNA regulation function and obtained 333 corresponding target genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional annotation were analysed, mostly including nucleic acid binding, plant hormone signal transduction, pantothenate and CoA biosynthesis, and cellulose synthase. This study will lay the foundation for clarifying the complex miRNA-mediated regulatory network for growth and development. In view of this, spatio-temporal expression of miR396, miR950, miR164, miR166 and miR160 were analysed in Larix olgensis during the growth stages of not lignified, beginning of lignification, and completely lignified in different tissues (root, stem, and leaf) by quantitative real-time PCR (qRT-PCR). There were differences in the expression of miRNAs in roots, stems and leaves in the same growth period. At 60 days, miR160, miR166 and miR396-2 exhibited the highest expression in leaves. At 120 days, most miRNAs in roots and stems decreased significantly. At 180 days, miRNAs were abundantly expressed in roots and stems. Meanwhile, analysis of the expression of miRNAs in leaves revealed that miR396-2 was reduced as time went on, whereas other miRNAs increased initially and then decreased. On the other hand, in the stems, miR166-1 was increase, whereas other miRNAs, especially miR160, miR164, miR396 and miR950-1, first decreased and then increased. Similarly, in the roots, miR950-2 first decreased and then increased, whereas other miRNAs exhibited a trend of continuous increase. CONCLUSIONS: The present investigation included rapid isolation and identification of miRNAs in Larix olgensis through construction of a sRNA library using Solexa and predicted 78 novel miRNAs, which showed differential expression levels in different tissues and stages. These results provided a theoretical basis for further revealing the genetic regulation mechanism of miRNA in the growth and development of conifers and the verification of function in target genes.


Assuntos
Regulação da Expressão Gênica de Plantas , Larix/genética , MicroRNAs/genética , RNA de Plantas/genética , Perfilação da Expressão Gênica , Biblioteca Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Larix/metabolismo , MicroRNAs/metabolismo , RNA de Plantas/metabolismo
7.
Sci Total Environ ; 679: 237-247, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31082597

RESUMO

Fire is an important disturbance agent in Chinese boreal forests but the long-term effects of wildfires on soil nitrogen (N) net mineralisation rates (Rmin) in natural versus human-assisted restorations are not well understood. In this study, we analysed upper (0-10cm) and lower layer (10-20cm) soil samples from natural restoration and afforestation plots in a Dahurian larch (Larix gmelinii) forest in north-eastern China 29years after a mega fire disturbance. Our results showed that the soil inorganic N (NH4+-N and NO3--N) pool of the upper and lower layers of the regenerated plots remained significantly lower than in unburned control plots. This suggests that the effects of a high burn severity fire on soil N availability were still significant almost 30years after the event. Restoration type (natural restoration versus afforestation) also had significant effects on upper layer soil N availability; compared with afforestation, natural restoration was more beneficial for the accumulation of soil inorganic N and the recovery of Rmin after fire disturbance. Specifically, the concentration of inorganic N and the mean Rmin in upper layer soils in the natural restoration plots were approximately 41% greater and 3.6 times greater, respectively, than in the afforestation plots. The differences in soil N availability between the two restoration types were attributed to differences in soil water content (SWC), soil microbial biomass nitrogen (MBN), and the recovery of vegetation after the fire disturbance. Our study demonstrates that natural restoration has proved more successful than afforestation in countering soil N losses in boreal forests in China resulting from a high burn severity fire disturbance.


Assuntos
Conservação dos Recursos Naturais , Incêndios , Larix/metabolismo , Nitrogênio/metabolismo , Solo/química , China , Agricultura Florestal , Florestas
8.
Ecotoxicology ; 28(5): 578-588, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31140045

RESUMO

Active urbanization processes exacerbate environmental problems associated with industrial pollution in cities. Urban greening helps reduce level of air pollution and improve microclimate. Selection sensitive plant species (indicators of pollution), and the resistant species (decrease the level pollution) is acute in many countries. The aim of the present work was to establish concentrations of heavy metals (Fe, Mn, Zn, Cu, Ni, Cr, Pb, Co and Cd) in the Siberian larch needles grown in various urban land-use (functional) zones of Ulan-Ude (Russia), as well as to determinate and compare the levels of some biochemical compounds. Based on index of soil contamination, the highest heavy metal pollution was found in the highway and industrial zones. The index of biogeochemical transformation of the needle elements composition ranged from 5.1 (minimal level) to 32.2 (strong level). The most polluted sites were along highways, where Fe, Zn, Cu, Cr, Ni, Pb, and Cd concentration in the needles were up to 2.5-7.7 times than background values. An important role in the protective system of larch is played by pigments, especially Chl b and carotenoids. Their content in the needles is increased by 1.3-2.2 times. Ratio Chl a/b and ∑Chl/carotenoids decrease as compared to background level; in the first case-due to increase of Chl b content, in the second case-increase of carotenoids level. Highest concentrations of proline, condensed tannins and peroxidase activity were found in needles from urban zones connected with high traffic and industrial emission. Based on the Air Pollution Tolerance Index Siberian larch should be considered sensitive species to air pollution and can be recommended as bioindicator.


Assuntos
Monitoramento Ambiental , Larix/metabolismo , Metais Pesados/metabolismo , Poluentes do Solo/metabolismo , Poluentes Atmosféricos/metabolismo , Larix/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Federação Russa
9.
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
10.
Carbohydr Res ; 467: 8-13, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30036728

RESUMO

Larch arabinogalactan (AG) is classified as a plant type II AG. Its basic structure is constituted by a ß-1,3-galactan main chain with ß-1,6-galactan side chains. But its properties are distinct from other type II AGs. Whereas most type II AGs are found as glycan moieties of arabinogalactan-protein (AGP), larch AG lacks a protein moiety. Larch AG itself is also unlike other type II AGs as it lacks Yariv reactivity, the capability of AG to form insoluble precipitate with ß-Yariv reagents, 1,3,5-tri-(p-glycosyloxyphenylazo)-2,4,6-trihydroxybenzene with ß-glucosyl or ß-galactosyl residues at the termini. For the present study, we prepared ß-galactan I, II, and III from larch AG by performing single, double, and triple Smith degradation, which breaks ß-1,6-galactan side chains, and examined Yariv reactivity of the products. Methylation analysis revealed that ß-galactans II and III had lost more than 90% of their ß-1,6-galactan branches. In the radial gel diffusion assay, ß-galactans II and III showed Yariv reactivity, indicating the presence of a Yariv-reactive structure in larch AG, although native larch AG does not have Yariv reactivity. The Yariv reactivity of the ß-galactans was completely lost after treatment with endo-ß-1,3-galactanase. These results confirm that ß-1,3-galactan is necessary for Yariv reactivity of type II AG. The present results also suggest that high substitution of ß-1,3-galactan with ß-1,6-galactan side chains affects Yariv reactivity in larch AG.


Assuntos
Galactanos/química , Glucosídeos/química , Larix/química , Floroglucinol/análogos & derivados , Madeira/química , Configuração de Carboidratos , Galactanos/síntese química , Galactanos/metabolismo , Glucosídeos/metabolismo , Larix/metabolismo , Floroglucinol/química , Floroglucinol/metabolismo , Madeira/metabolismo
11.
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
12.
Isotopes Environ Health Stud ; 54(1): 63-77, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28780887

RESUMO

Soil moisture is a major factor controlling carbon isotope discrimination (Δ13C), which has been demonstrated to decrease under dry conditions in many studies; however, few studies on Δ13C under waterlogging condition have been conducted. In this study, a pot experiment was conducted with Larix gmelinii, a major larch species in the east Siberian Taiga, to investigate the effect of waterlogging on Δ13C during photosynthesis. Assimilation rate and Δ13CRD (instantaneous Δ13C calculated with Rayleigh distillation equation) decreased drastically soon after waterlogging, followed by recovery in their values, which was caused by a change in stomatal conductance. Thereafter, assimilation rate decreased gradually, whereas Δ13CRD decreased more gently. These results were thought to be caused by the decrease in both stomatal conductance and carboxylation. Our results indicate that extreme wet events may cause a decrease in Δ13C, which is important information for detecting flooding events in the past using tree-ring isotope analyses and for studying impacts of flooding on plants in areas where waterlogging might occur.


Assuntos
Isótopos de Carbono/análise , Inundações , Larix/metabolismo , Fotossíntese , Monitoramento Ambiental
13.
PLoS One ; 12(12): e0189424, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29244849

RESUMO

Elucidating the stoichiometry and resorption patterns of multiple nutrients is of essential importance to holistically understanding plant nutrition and biogeochemical cycling. Although many studies on ecological stoichiometry have been carried out, surprisingly few of them were simultaneously done on the investigation of both nutrient resorption efficiency and stoichiometry for different-aged plantations of a perennial tree. Here, both green and senesced leaf samples were collected from four Larix kaempfer plantations aged of 8, 15, 22, and 32 years in the Qinling Mountains to examine nutrients resorption efficiency and stoichiometry characteristics. The results suggested that the nutrient concentrations of N, P, K, Ca, Mg, Al, and Fe in both green and senesced leaves of L. kaempferi (a deciduous conifer tree) did not show a regular change trends along the plantation ages in the Qinling Mountains. The concentrations of the most nutrients examined, except for Fe, in the green leaves were relatively lower than or close to the required physiological concentrations, suggesting a relative limitation of multiple nutrients exists in L. kaempferi for its above-ground biomass growth. The rank order of resorption efficiencies of four key nutrients (N, P, K, and Mg) was K (80.89%) > N (67.42%) > P (65.34%) > Mg (41.16%), whereas the nutrient Ca and Fe tended to accumulate in senesced leaves. Overall, the nutrient resorption efficiency of all examined elements did not exhibit a regular trend corresponding to the change of the plantation ages in L. kaempferi, but it was positively related to the nutrient concentrations in green leaves. The mean C:N and C:P ratios in the green and senesced leaves were significantly higher than those reported globally (on average). By contrast, the N:P ratio, at <14, was not only much lower than that reported for both China's flora and globally (on average), but it did suggest that the N nutrient limits growth of L. kaempferi in these plantations. Taken together, the results of this study are of substantial interest and value to forest managers and for the sustainable development of the Qinling forest ecosystems.


Assuntos
Larix/metabolismo , Folhas de Planta/metabolismo , Carbono/análise , Carbono/metabolismo , China , Larix/química , Nitratos/análise , Nitratos/metabolismo , Fosfatos/análise , Fosfatos/metabolismo , Folhas de Planta/química , Solo/química
14.
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
15.
Plant Cell Physiol ; 58(3): 587-597, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28158764

RESUMO

The endosymbiotic theory states that plastids are derived from a single cyanobacterial ancestor that possessed a cell wall. Peptidoglycan (PG), the main component of the bacteria cell wall, gradually degraded during plastid evolution. PG-synthesizing Mur genes have been found to be retained in the genomes of basal streptophyte plants, although many of them have been lost from the genomes of angiosperms. The enzyme encoded by bacterial MurE genes catalyzes the formation of the UDP-N-acetylmuramic acid (UDP-MurNAc) tripeptide in bacterial PG biosynthesis. Knockout of the MurE gene in the moss Physcomitrella patens resulted in defects of chloroplast division, whereas T-DNA-tagged mutants of Arabidopsis thaliana for MurE revealed inhibition of chloroplast development but not of plastid division, suggesting that AtMurE is functionally divergent from the bacterial and moss MurE proteins. Here, we could identify 10 homologs of bacterial Mur genes, including MurE, in the recently sequenced genomes of Picea abies and Pinus taeda, suggesting the retention of the plastid PG system in gymnosperms. To investigate the function of gymnosperm MurE, we isolated an ortholog of MurE from the larch, Larix gmelinii (LgMurE) and confirmed its presence as a single copy per genome, as well as its abundant expression in the leaves of larch seedlings. Analysis with a fusion protein combining green fluorescent protein and LgMurE suggested that it localizes in chloroplasts. Cross-species complementation assay with MurE mutants of A. thaliana and P. patens showed that the expression of LgMurE cDNA completely rescued the albefaction defects in A. thaliana but did not rescue the macrochloroplast phenotype in P. patens. The evolution of plastid PG and the mechanism behind the functional divergence of MurE genes are discussed in the context of information about plant genomes at different evolutionary stages.


Assuntos
Arabidopsis/genética , Cycadopsida/genética , Larix/genética , Proteínas de Ligação às Penicilinas/genética , Peptidoglicano/genética , Fenótipo , Proteínas de Plantas/genética , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/genética , Bryopsida/genética , Bryopsida/metabolismo , Parede Celular/genética , Parede Celular/metabolismo , Cloroplastos/genética , Cloroplastos/metabolismo , Cianobactérias/genética , Cianobactérias/metabolismo , Cycadopsida/metabolismo , DNA Bacteriano , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Genes Bacterianos , Genes de Plantas , Genoma de Planta , Proteínas de Fluorescência Verde , Larix/metabolismo , Magnoliopsida/genética , Mutação , Proteínas de Ligação às Penicilinas/metabolismo , Peptidoglicano/metabolismo , Picea/genética , Pinus taeda/genética , Folhas de Planta/genética , Proteínas de Plantas/metabolismo , Plastídeos/genética , Plastídeos/metabolismo , Sementes/genética , Sementes/metabolismo
16.
Proc Natl Acad Sci U S A ; 114(5): 974-979, 2017 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-28096378

RESUMO

The diversity of small molecules formed via plant diterpene metabolism offers a rich source of known and potentially new biopharmaceuticals. Among these, the microtubule-destabilizing activity of pseudolaric acid B (PAB) holds promise for new anticancer agents. PAB is found, perhaps uniquely, in the coniferous tree golden larch (Pseudolarix amabilis, Pxa). Here we describe the discovery and mechanistic analysis of golden larch terpene synthase 8 (PxaTPS8), an unusual diterpene synthase (diTPS) that catalyzes the first committed step in PAB biosynthesis. Mining of the golden larch root transcriptome revealed a large TPS family, including the monofunctional class I diTPS PxaTPS8, which converts geranylgeranyl diphosphate into a previously unknown 5,7-fused bicyclic diterpene, coined "pseudolaratriene." Combined NMR and quantum chemical analysis verified the structure of pseudolaratriene, and co-occurrence with PxaTPS8 and PAB in P amabilis tissues supports the intermediacy of pseudolaratriene in PAB metabolism. Although PxaTPS8 adopts the typical three-domain structure of diTPSs, sequence phylogeny places the enzyme with two-domain TPSs of mono- and sesqui-terpene biosynthesis. Site-directed mutagenesis of PxaTPS8 revealed several catalytic residues that, together with quantum chemical calculations, suggested a substantial divergence of PxaTPS8 from other TPSs leading to a distinct carbocation-driven reaction mechanism en route to the 5,7-trans-fused bicyclic pseudolaratriene scaffold. PxaTPS8 expression in microbial and plant hosts provided proof of concept for metabolic engineering of pseudolaratriene.


Assuntos
Alquil e Aril Transferases/metabolismo , Diterpenos/metabolismo , Larix/metabolismo , Proteínas de Plantas/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , Agrobacterium tumefaciens/genética , Agrobacterium tumefaciens/metabolismo , Alquil e Aril Transferases/genética , Sequência de Aminoácidos , Domínio Catalítico , Clonagem Molecular , DNA Complementar/genética , Larix/enzimologia , Larix/genética , Mutagênese Sítio-Dirigida , Proteínas de Plantas/genética , Raízes de Plantas/enzimologia , Interferência de RNA , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/metabolismo , Alinhamento de Sequência
17.
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
18.
Int J Mol Sci ; 17(11)2016 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-27879674

RESUMO

Hydrogen is a therapeutic antioxidant that has been used extensively in clinical trials. It also acts as a bioactive molecule that can alleviate abiotic stress in plants. However, the biological effects of hydrogen in somatic embryos and the underlying molecular basis remain largely unknown. In this study, the morphological and physiological influence of exogenous H2 treatment during somatic embryogenesis was characterized in Larix leptolepis Gordon. The results showed that exposure to hydrogen increased the proportions of active pro-embryogenic cells and normal somatic embryos. We sequenced mRNA and microRNA (miRNA) libraries to identify global transcriptome changes at different time points during H2 treatment of larch pro-embryogenic masses (PEMs). A total of 45,393 mRNAs and 315 miRNAs were obtained. Among them, 4253 genes and 96 miRNAs were differentially expressed in the hydrogen-treated libraries compared with the control. Further, a large number of the differentially expressed mRNAs and miRNAs were related to reactive oxygen species (ROS) homeostasis and cell cycle regulation. We also identified 4399 potential target genes for 285 of the miRNAs. The differential expression data and the mRNA-miRNA interaction network described here provide new insights into the molecular mechanisms that determine the performance of PEMs exposed to H2 during somatic embryogenesis.


Assuntos
Regulação da Expressão Gênica de Plantas , Hidrogênio/farmacologia , Larix/efeitos dos fármacos , MicroRNAs/genética , RNA Mensageiro/genética , Sementes/efeitos dos fármacos , Transcriptoma , Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Biblioteca Gênica , Redes Reguladoras de Genes/efeitos dos fármacos , Larix/genética , Larix/crescimento & desenvolvimento , Larix/metabolismo , MicroRNAs/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Técnicas de Embriogênese Somática de Plantas , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sementes/genética , Sementes/crescimento & desenvolvimento , Sementes/metabolismo
19.
Tree Physiol ; 36(8): 942-53, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27468738

RESUMO

We aim to achieve a mechanistic understanding of the eco-physiological processes in Larix decidua and Pinus mugo var. uncinata growing on north- and south-facing aspects in the Swiss National Park in order to distinguish the short- and long-term effects of a changing climate. To strengthen the interpretation of the δ(18)O signal in tree rings and its coherence with the main factors and processes driving evaporative δ(18)O needle water enrichment, we analyzed the δ(18)O in needle, xylem and soil water over the growing season in 2013 and applied the mechanistic Craig-Gordon model (1965) for the short-term responses. We found that δ(18)O needle water strongly reflected the variability of relative humidity mainly for larch, while only δ(18)O in pine xylem water showed a strong link to δ(18)O in precipitation. Larger differences in offsets between modeled and measured δ(18)O needle water for both species from the south-facing aspects were detected, which could be explained by the high transpiration rates. Different soil water and needle water responses for the two species indicate different water-use strategies, further modulated by the site conditions. To reveal the long-term physiological response of the studied trees to recent and past climate changes, we analyzed δ(13)C and δ(18)O in wood chronologies from 1900 to 2013. Summer temperatures as well as summer and annual amount of precipitations are important factors for growth of both studied species from both aspects. However, mountain pine trees reduced sensitivity to temperature changes, while precipitation changes come to play an important role for the period from 1980 to 2013. Intrinsic water-use efficiency (WUEi) calculated for larch trees since the 1990s reached a saturation point at elevated CO2 Divergent trends between pine WUEi and δ(18)O are most likely indicative of a decline of mountain pine trees and are also reflected in decoupling mechanisms in the isotope signals between needles and tree-rings.


Assuntos
Mudança Climática , Larix/metabolismo , Larix/fisiologia , Pinus/metabolismo , Pinus/fisiologia , Água/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Xilema/metabolismo
20.
New Phytol ; 212(4): 1019-1029, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27400237

RESUMO

The imbalance between nitrogen (N) and phosphorus (P) deposition may shift temperate ecosystems from N- to P-limitation. However, it is unclear how the imbalanced N : P input affects the strategies of plants to acquire P and, therefore, the growth of plants and the competition among species. We conducted a 4-yr N-addition experiment in young and mature larch (Larix principis-rupprechtii) stands. Plant growth and P acquisition strategies were assessed for larch and understorey vegetation. N addition stimulated the aboveground productivity of understorey vegetation in the young stand and larch in the mature stand, with other species unaffected. The competitive advantages of understorey vegetation in the young stand and larch in the mature stand were associated with their high stoichiometric homoeostasis. To maintain the N : P homoeostasis of these species, an increase in phosphatase activity but not P resorption efficiency increased the supply of P. Additionally, N addition accelerated P mineralization by decreasing the fungal-to-bacterial ratios and improved uptake of soil P by increasing the arbuscular mycorrhizas-to-ectomycorrhizas ratios. Our results suggest that plants with high stoichiometric homoeostasis could better cope with N deposition-induced P-deficiency. Although P resorption efficiency showed little plasticity in response, plants activated a variety of P-acquisition pathways to alleviate the P-deficiency caused by N deposition.


Assuntos
Larix/metabolismo , Nitrogênio/metabolismo , Fosfatos/metabolismo , Fósforo/deficiência , Fosfatase Ácida/metabolismo , Análise de Variância , Bactérias/metabolismo , Biomassa , Ácidos Graxos/metabolismo , Fungos/fisiologia , Homeostase , Micorrizas/fisiologia , Fosfolipídeos/metabolismo , Fósforo/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Especificidade da Espécie
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