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1.
Plant Sci ; 290: 110301, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779889

RESUMO

Histone deacetylases (HDACs) regulate gene transcription, and play a critical role in plant growth, development and stress responses. HD2 proteins are plant specific histone deacetylases. In woody plants, functions of HD2s are not known. In this study, we cloned an HD2 gene PtHDT902 from Populus trichocarpa and investigated its sequence, expression, subcellular localization, and functions in root development and salt stress responses. Our findings indicated that PtHDT902 was a nuclear protein and its expression was regulated by abiotic stresses. The over-expression of PtHDT902 in both Arabidopsis and poplar increased the expression levels of gibberellin (GA) biosynthetic genes. The expression of PtHDT902 in Arabidopsis enhanced primary root growth, and its over-expression in poplar inhibited adventitious root formation. These phenotypes resulted from over-expression of PtHDT902 were consistent with the GA-overproduction phenotypes. In addition, the poplar plants over-expressing PtHDT902 exhibited lower tolerance to salt than non-transgenic plants. These findings indicated that PtHDT902 worked as an important regulator in adventitious root formation and salt stress tolerance in poplar.


Assuntos
Histona Desacetilases/genética , Proteínas de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Populus/fisiologia , Tolerância ao Sal/genética , Sequência de Aminoácidos , Giberelinas/metabolismo , Histona Desacetilases/química , Histona Desacetilases/metabolismo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Populus/genética , Populus/crescimento & desenvolvimento , Alinhamento de Sequência
2.
Plant Sci ; 288: 110224, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31521213

RESUMO

Patatin-liked phospholipase A (pPLAs) are major lipid acyl hydrolases that participate in various biological functions in plant growth and development. Previously, a ginseng-derived pPLAIII homolog was reported to reduce lignin content in Arabidopsis. This led us to evaluate its possible usefulness as a biomass source in wood plant. Herein, we report that there are six members in the pPLAIII gene family in poplar. Overexpression of pPLAIIIß derived from ginseng resulted in a reduced plant height with radially expanded stem growth in hybrid poplars. Compared with the wild type (WT), the chlorophyll content was increased in the overexpression poplar lines, whereas the leaf size was smaller. The secondary cell wall structure in overexpression lines was also altered, exhibiting reduced lignification in the xylem. Two transcription factors, MYB92 and MYB152, which control lignin biosynthesis, were downregulated in the overexpression lines. The middle xylem of the overexpression line showed heavy thickening, making it thicker than the other xylem parts and the WT xylem, which rather could have been contributed by the presence of more cellulose in the selected surface area. Taken together, the results suggest that PgpPLAIIIß plays a role not only in cell elongation patterns, but also in determining the secondary cell wall composition.


Assuntos
Lignina/metabolismo , Panax/genética , Fosfolipases A/genética , Proteínas de Plantas/genética , Populus/genética , Madeira/crescimento & desenvolvimento , Sequência de Aminoácidos , Regulação da Expressão Gênica de Plantas , Lignina/genética , Panax/química , Fosfolipases A/química , Fosfolipases A/metabolismo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Populus/crescimento & desenvolvimento , Alinhamento de Sequência , Madeira/genética , Xilema/genética , Xilema/crescimento & desenvolvimento
3.
Genes (Basel) ; 10(9)2019 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-31500311

RESUMO

Wood, the most abundant biomass on Earth, is composed of secondary xylem differentiated from vascular cambium. However, the underlying molecular mechanisms of wood formation remain largely unclear. To gain insight into wood formation, we performed a series of wood-forming tissue-specific transcriptome analyses from a hybrid poplar (Populus alba × P. glandulosa, clone BH) using RNA-seq. Together with shoot apex and leaf tissue, cambium and xylem tissues were isolated from vertical stem segments representing a gradient of secondary growth developmental stages (i.e., immature, intermediate, and mature stem). In a comparative transcriptome analysis of the 'developing xylem' and 'leaf' tissue, we could identify critical players catalyzing each biosynthetic step of secondary wall components (e.g., cellulose, xylan, and lignin). Several candidate genes involved in the initiation of vascular cambium formation were found via a co-expression network analysis using abundantly expressed genes in the 'intermediate stem-derived cambium' tissue. We found that transgenic Arabidopsis plants overexpressing the PtrHAM4-1, a GRAS family transcription factor, resulted in a significant increase of vascular cambium development. This phenotype was successfully reproduced in the transgenic poplars overexpressing the PtrHAM4-1. Taken together, our results may serve as a springboard for further research to unravel the molecular mechanism of wood formation, one of the most important biological processes on this planet.


Assuntos
Câmbio/genética , Parede Celular/genética , Populus/genética , Transcriptoma , Câmbio/crescimento & desenvolvimento , Parede Celular/metabolismo , Lignina/biossíntese , Lignina/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Caules de Planta/genética , Caules de Planta/crescimento & desenvolvimento , Populus/crescimento & desenvolvimento , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Xilanos/biossíntese , Xilanos/genética , Xilema/genética , Xilema/crescimento & desenvolvimento
4.
Mol Genet Genomics ; 294(6): 1511-1525, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31324970

RESUMO

DNA methylation and long non-coding RNAs (lncRNAs) regulate plant growth and development, but their relationship and effect on responses to the auxin phytohormone indole-3-acetic acid (IAA) remain largely unknown, particularly in woody plants such as poplar (Populus tomentosa). Following treatment of 1-year-old clonal plants with 100 µM IAA, key poplar lncRNA genes showed changes in methylation, but whole-genome methylation levels showed no significant change. Moreover, 100 µM IAA inhibited growth of the 1-year-old poplar clones, possibly through the suppression of photosynthesis. This inhibition had a long-term effect, persisting at 1 month after removal of the exogenous IAA. Transcriptome analysis identified two candidate lncRNA genes that show changes in expression following IAA treatment, TCONS_00003480 and TCONS_00004832. TCONS_00003480 contains the same microRNA target sites of ptc-miR6464 as the 4-coumarate: CoA ligase 2 transcript, which encodes a lignin biosynthesis enzyme. And TCONS_00004832 shares the same target sites of ptc-miR6437a with the Photosystem II reaction center protein D and Cytochrome C Oxidase 17 transcripts, which are related to photosynthesis. The two lncRNAs as the mimics to corresponding target genes of miRNAs to prevent them from degrading. Examination of lncRNA gene expression and methylation revealed a negative relationship (r = - 0.29, P < 0.05); moreover, hypermethylation of the two candidate lncRNA genes remained 1 month after IAA treatment, suggesting that changes in methylation might be involved in the long-term effects of plant hormones. Therefore, our study reveals a long-term effect of IAA on the growth of P. tomentosa, possibly via methylation-mediated epigenetic changes in lncRNA gene expression and the interaction with corresponding miRNAs, leading to regulation of genes related to photosynthesis and growth.


Assuntos
Metilação de DNA , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos/farmacologia , Reguladores de Crescimento de Planta/farmacologia , Populus/genética , RNA Longo não Codificante/genética , Parede Celular/metabolismo , Metilação de DNA/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , MicroRNAs/metabolismo , Fotossíntese/efeitos dos fármacos , Populus/efeitos dos fármacos , Populus/crescimento & desenvolvimento , Populus/metabolismo , RNA Longo não Codificante/metabolismo
5.
BMC Plant Biol ; 19(1): 276, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234799

RESUMO

BACKGROUND: Aspartic protease (AP) is one of four large proteolytic enzyme families that are involved in plant growth and development. Little is known about the AP gene family in tree species, although it has been characterized in Arabidopsis, rice and grape. The AP genes that are involved in tree wood formation remain to be determined. RESULTS: A total of 67 AP genes were identified in Populus trichocarpa (PtAP) and classified into three categories (A, B and C). Chromosome mapping analysis revealed that two-thirds of the PtAP genes were located in genome duplication blocks, indicating the expansion of the AP family by segmental duplications in Populus. The microarray data from the Populus eFP browser demonstrated that PtAP genes had diversified tissue expression patterns. Semi-qRT-PCR analysis further determined that more than 10 PtAPs were highly or preferentially expressed in the developing xylem. When the involvement of the PtAPs in wood formation became the focus, many SCW-related cis-elements were found in the promoters of these PtAPs. Based on PtAPpromoter::GUS techniques, the activities of PtAP66 promoters were observed only in fiber cells, not in the vessels of stems as the xylem and leaf veins developed in the transgenic Populus tree, and strong GUS signals were detected in interfascicular fiber cells, roots, anthers and sepals of PtAP17promoter::GUS transgenic plants. Intensive GUS activities in various secondary tissues implied that PtAP66 and PtAP17 could function in wood formation. In addition, most of the PtAP proteins were predicted to contain N- and (or) O-glycosylation sites, and the integration of PNGase F digestion and western blotting revealed that the PtAP17 and PtAP66 proteins were N-glycosylated in Populus. CONCLUSIONS: Comprehensive characterization of the PtAP genes suggests their functional diversity during Populus growth and development. Our findings provide an overall understanding of the AP gene family in trees and establish a better foundation to further describe the roles of PtAPs in wood formation.


Assuntos
Ácido Aspártico Proteases/genética , Genes de Plantas , Família Multigênica , Proteínas de Plantas/genética , Populus/genética , Madeira/crescimento & desenvolvimento , Parede Celular/genética , Sequência Conservada , Duplicação Gênica , Perfilação da Expressão Gênica , Glicosilação , Filogenia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Populus/enzimologia , Populus/crescimento & desenvolvimento , Regiões Promotoras Genéticas
6.
BMC Plant Biol ; 19(1): 279, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31242858

RESUMO

BACKGROUND: Seed germination, a complex, physiological-morphogenetic process, is a critical stage in the life cycle of plants. Biological changes in germinating seeds have not been investigated in poplar, a model woody plant. RESULTS: In this study, we exploited next-generation sequencing and metabolomics analysis and uncovered a series of significantly different genes and metabolites at various stages of seed germination and post germination. The K-means method was used to identify multiple transcription factors, including AP2/EREBP, DOF, and YABBY, involved in specific seed germination and post-germination stages. A weighted gene coexpression network analysis revealed that cell wall, amino acid metabolism, and transport-related pathways were significantly enriched during stages 3 and 5, with no significant enrichment observed in primary metabolic processes such as glycolysis and the tricarboxylic acid cycle. A metabolomics analysis detected significant changes in intermediate metabolites in these primary metabolic processes, while a targeted correlation network analysis identified the gene family members most relevant to these changing metabolites. CONCLUSIONS: Taken together, our results provide important insights into the molecular networks underlying poplar seed germination and post-germination processes. The targeted correlation network analysis approach developed in this study can be applied to search for key candidate genes in specific biochemical reactions and represents a new strategy for joint multiomics analyses.


Assuntos
Germinação , Proteínas de Plantas/genética , Populus/genética , Sementes/crescimento & desenvolvimento , Fatores de Transcrição/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Germinação/genética , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Sementes/genética , Fatores de Transcrição/metabolismo
7.
BMC Plant Biol ; 19(1): 251, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31185907

RESUMO

BACKGROUND: Compared with annual herbaceous plants, woody perennials require a longer period of juvenile phase to flowering, and many traits can be only expressed in adulthood, which seriously makes the breeding efficiency of new varieties slower. For the study of poplar early flowering, the main focus is on the study Arabidopsis homologue gene CO/FT. Based on studies of Arabidopsis, rice and other plant species, some important research progress has been made on the regulation of flowering time by NF-Y subunits. However, little is known about the function of NF-Y regulating flowering in poplar. RESULTS: In the present study, we have identified PtNF-YB family members in poplar and focus on the function of the PtNF-YB1 regulate flowering timing using transgenic Arabidopsis and tomato. To understand this mechanisms, the expression levels of three known flowering genes (CO, FT and SOC1) were examined with RT-PCR in transgenic Arabidopsis. We used the Y2H and BiFC to assay the interactions between PtNF-YB1 and PtCO (PtCO1 and PtCO2) proteins. Finally, the potential molecular mechanism model in which PtNF-YB1 play a role in regulating flowering in poplar was discussed. CONCLUSIONS: In this study, we have characterized the poplar NF-YB gene family and confirmed the function of the PtNF-YB1 regulate flowering timing. At the same time, we found that the function of PtNF-YB1 to improve early flowering can overcome species barriers. Therefore, PtNF-YB1 can be used as a potential candidate gene to improve early flowering by genetic transformation in poplar and other crops.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Proteínas de Plantas/genética , Populus/crescimento & desenvolvimento , Populus/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Arabidopsis/genética , Sequência de Bases , Flores/genética , Flores/crescimento & desenvolvimento , Família Multigênica , Fenótipo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Populus/metabolismo , Alinhamento de Sequência , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
8.
Genes (Basel) ; 10(6)2019 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-31195761

RESUMO

BACKGROUND: Cold tolerance is important for plants' geographical distribution and survival in extreme seasonal variations of climate. However, Populus simonii × P. nigra shows wide adaptability and strong cold resistance. Transcriptional and post-transcriptional regulation of cold-responsive genes is crucial for cold tolerance in plants. To understand the roles of regulatory RNAs under cold induction in Populus simonii × P. nigra, we constructed cDNA and small RNA libraries from leaf buds treated or not with -4 °C for 8 h for analysis. RESULTS: Through high-throughput sequencing and differential expression analysis, 61 miRNAs and 1229 DEGs were identified under cold induction condition in Populus simonii × P. nigra. The result showed that miR167a, miR1450, miR319a, miR395b, miR393a-5p, miR408-5p, and miR168a-5p were downregulated, whereas transcription level of miR172a increased under the cold treatment. Thirty-one phased-siRNA were also obtained (reads ≥ 4) and some of them proceeded from TAS3 loci. Analysis of the differentially expressed genes (DEGs) showed that transcription factor genes such as Cluster-15451.2 (putative MYB), Cluster-16493.29872 (putative bZIP), Cluster-16493.29175 (putative SBP), and Cluster-1378.1 (putative ARF) were differentially expressed in cold treated and untreated plantlets of Populus simonii × P. nigra. Integrated analysis of miRNAs and transcriptome showed miR319, miR159, miR167, miR395, miR390, and miR172 and their target genes, including MYB, SBP, bZIP, ARF, LHW, and ATL, were predicted to be involved in ARF pathway, SPL pathway, DnaJ related photosystem II, and LRR receptor kinase, and many of them are known to resist chilling injury. Particularly, a sophisticated regulatory model including miRNAs, phasiRNAs, and targets of them was set up. CONCLUSIONS: Integrated analysis of miRNAs and transcriptome uncovered the complicated regulation of the tolerance of cold in Populus simonii × P. nigra. MiRNAs, phasiRNAs, and gene-encoded transcription factors were characterized at a whole genome level and their expression patterns were proved to be complementary. This work lays a foundation for further research of the pathway of sRNAs and regulatory factors involved in cold tolerance.


Assuntos
Resposta ao Choque Frio/genética , MicroRNAs/genética , Populus/genética , Transcriptoma/genética , Regulação da Expressão Gênica de Plantas , Sequenciamento de Nucleotídeos em Larga Escala , Proteínas de Plantas/genética , Populus/crescimento & desenvolvimento , RNA Mensageiro/genética
9.
Environ Monit Assess ; 191(7): 465, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31243568

RESUMO

The germination capacity of poplar seeds has never been studied in the context of metal(loid)-contaminated soils, even though poplars are present over a vast geographical area. In this study, black poplar seeds from the Loire Valley (France) were grown for 28 days in mesocosm on a heavily polluted soil that was subjected to different amendments. This phytomanagement process aimed to allow the revegetation of an As and Pb-contaminated mining soil by adding appropriate amendments, resulting in metal(loid) soil stabilisation and efficient plant growth. The objectives were to evaluate the effect of three amendments (garden soil, compost and biochar) when added alone or combined to a technosol on (i) the soil physicochemical properties, (ii) the mobility of As and Pb in the soil pore water (SPW), (iii) the capacity of poplar seeds to germinate and to grow and (iv) the metal(loid) distribution within the plant organs. The addition of amendments alone or combined allowed a 90% decrease in SPW Pb concentrations, while the arsenic concentrations were between 18 and 416 times higher. However, we were only able to obtain seed germination and plant growth on amended soils. These promising results will allow us to explore the use of such amendments in rehabilitating areas that are sources of significant metal(loid) dissemination, as well as allowing a natural plant recolonisation of these sites by seeds from the surrounding environment.


Assuntos
Carvão Vegetal/química , Compostagem , Germinação/efeitos dos fármacos , Mineração , Populus/efeitos dos fármacos , Poluentes do Solo/análise , Solo/química , Arsênico/análise , Monitoramento Ambiental , França , Chumbo/análise , Chumbo/toxicidade , Populus/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Poluentes do Solo/toxicidade
10.
New Phytol ; 223(4): 2076-2089, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31104343

RESUMO

The genomic architecture of functionally important traits is key to understanding the maintenance of reproductive barriers and trait differences when divergent populations or species hybridize. We conducted a genome-wide association study (GWAS) to study trait architecture in natural hybrids of two ecologically divergent Populus species. We genotyped 472 seedlings from a natural hybrid zone of Populus alba and Populus tremula for genome-wide markers from reduced representation sequencing, phenotyped the plants in common gardens for 46 phytochemical (phenylpropanoid), morphological and growth traits, and used a Bayesian polygenic model for mapping. We detected three classes of genomic architectures: traits with finite, detectable associations of genetic loci with phenotypic variation in addition to highly polygenic heritability; traits with indications for polygenic heritability only; and traits with no detectable heritability. For the first class, we identified genome regions with plausible candidate genes for phenylpropanoid biosynthesis or its regulation, including MYB transcription factors and glycosyl transferases. GWAS in natural, recombinant hybrids represent a promising step towards resolving the genomic architecture of phenotypic traits in long-lived species. This facilitates the fine-mapping and subsequent functional characterization of genes and networks causing differences in hybrid performance and fitness.


Assuntos
Mapeamento Cromossômico , Genoma de Planta , Hibridização Genética , Compostos Fitoquímicos/metabolismo , Populus/crescimento & desenvolvimento , Populus/genética , Característica Quantitativa Herdável , Estudo de Associação Genômica Ampla , Desequilíbrio de Ligação/genética , Fenótipo , Populus/anatomia & histologia , Probabilidade , Especificidade da Espécie
11.
New Phytol ; 223(4): 1888-1903, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31081152

RESUMO

Occurrence of stomata on both leaf surfaces (amphistomaty) promotes higher stomatal conductance and photosynthesis while simultaneously increasing exposure to potential disease agents in black cottonwood (Populus trichocarpa). A genome-wide association study (GWAS) with 2.2M single nucleotide polymorphisms generated through whole-genome sequencing found 280 loci associated with variation in adaxial stomatal traits, implicating genes regulating stomatal development and behavior. Strikingly, numerous loci regulating plant growth and response to biotic and abiotic stresses were also identified. The most significant locus was a poplar homologue of SPEECHLESS (PtSPCH1). Individuals possessing PtSPCH1 alleles associated with greater adaxial stomatal density originated primarily from environments with shorter growing seasons (e.g. northern latitudes, high elevations) or with less precipitation. PtSPCH1 was expressed in developing leaves but not developing stem xylem. In developing leaves, RNA sequencing showed patterns of coordinated expression between PtSPCH1 and other GWAS-identified genes. The breadth of our GWAS results suggests that the evolution of amphistomaty is part of a larger, complex response in plants. Suites of genes underpin this response, retrieved through genetic association to adaxial stomata, and show coordinated expression during development. We propose that the occurrence of amphistomaty in P. trichocarpa involves PtSPCH1 and reflects selection for supporting rapid growth over investment in immunity.


Assuntos
Padronização Corporal , Proteínas de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Populus/fisiologia , Alelos , Clima , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Estudo de Associação Genômica Ampla , Genótipo , Geografia , Fenótipo , Desenvolvimento Vegetal , Imunidade Vegetal/genética , Proteínas de Plantas/genética , Estômatos de Plantas/genética , Polimorfismo de Nucleotídeo Único/genética , Populus/genética , Populus/crescimento & desenvolvimento , Populus/imunologia , Característica Quantitativa Herdável , Especificidade da Espécie
12.
PLoS One ; 14(5): e0217066, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31141527

RESUMO

Certain plant genotypes can achieve optimal growth under appropriate environmental conditions. Under high planting density conditions, plants undergo competition for uptake and utilization of light and nutrients. However, the relationship between whole-genome expression patterns and the planting density in perennial woody plants remains unknown. In this study, whole-genome RNA sequencing of poplar (Populus × euramericana) was carried out at three different sampling heights to determine gene expression patterns under high (HD) and low (LD) planting densities. As a result, 4,004 differentially expressed genes (DEGs) were detected between HD and LD, of which 2,300, 701, and 1,003 were detected at the three positions, upper, middle and bottom, respectively. Function annotation results further revealed that a large number of the DEGs were involved in distinct biological functions. There were significant changes in the expression of metabolism-related and stimulus-related genes in response to planting density. There were 37 DEGs that were found at all three positions and were subsequently screened. Several DEGs related to plant light responses and photosynthesis were observed at different positions. Meanwhile, numbers of genes related to auxin/indole-3-acetic acid, and carbon and nitrogen metabolism were also revealed, displaying overall trends of upregulation under HD. These findings provide a basis for identifying candidate genes related to planting density and could increase our molecular understanding of the effect of planting density on gene expression.


Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Populus/genética , Transcriptoma , Densidade Demográfica , Populus/crescimento & desenvolvimento
13.
Integr Comp Biol ; 59(3): 559-570, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31127304

RESUMO

Climate change has resulted in increased temperature means across the globe. Many angiosperms flower earlier in response to rising temperature and the phenologies of these species are reasonably well predicted by models that account for spring (early growing season) and winter temperatures. Surprisingly, however, exceptions to the general pattern of precocious flowering are common. Many species either do not appear to respond or even delay flowering in, or following, warm growing seasons. Existing phenological models have not fully addressed such exceptions to the common association of advancing phenologies with warming temperatures. The phenological events that are typically recorded (e.g., onset of flowering) are but one phase in a complex developmental process that often begins one or more years previously, and flowering time may be strongly influenced by temperature over the entire multi-year course of flower development. We propose a series of models that explore effects of growing-season temperature increase on the multiple processes of flower development and how changes in development may impact the timing of anthesis. We focus on temperate forest trees, which are characterized by preformation, the initiation of flower primordia one or more years prior to anthesis. We then synthesize the literature on flower development to evaluate the models. Although fragmentary, the existing data suggest the potential for temperature to affect all aspects of flower development in woody perennials. But, even for relatively well studied taxa, the critical developmental responses that underlie phenological patterns are difficult to identify. Our proposed models explain the seemingly counter-intuitive observations that warmer growing-season temperatures delay flowering in many species. Future research might concentrate on taxa that do not appear to respond to temperature, or delay flowering in response to warm temperatures, to understand what processes contribute to this pattern.


Assuntos
Flores/crescimento & desenvolvimento , Aquecimento Global , Populus/crescimento & desenvolvimento , Rosaceae/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Modelos Biológicos , Reprodução
14.
Plant Mol Biol ; 100(3): 303-317, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30945147

RESUMO

KEY MESSAGE: Overexpression of the poplar PP2C protein phosphatase gene PtrHAB2 resulted in increased tree height and altered leaf morphology and phyllotaxy, implicating PP2C phosphatases as growth regulators functioning under favorable conditions. We identified and studied Populus trichocarpa genes, PtrHAB1 through PtrHAB15, belonging to the clade A PP2C family of protein phosphatases known to regulate abscisic acid (ABA) signaling. PtrHAB1 through PtrHAB3 and PtrHAB12 through PtrHAB15 were the most highly expressed genes under non-stress conditions. The poplar PP2C genes were differentially regulated by drought treatments. Expression of PtrHAB1 through PtrHAB3 was unchanged or downregulated in response to drought, while all other PtrHAB genes were weakly to strongly upregulated in response to drought stress treatments. Yeast two-hybrid assays involving seven ABA receptor proteins (PtrRCAR) against 12 PtrHAB proteins detected 51 interactions involving eight PP2Cs and all PtrRCAR proteins with 22 interactions requiring the addition of ABA. PtrHAB2, PtrHAB12, PtrHAB13 and PtrHAB14 also interacted with the sucrose non-fermenting related kinase 2 proteins PtrSnRK2.10 and PtrSnRK2.11, supporting conservation of a SnRK2 signaling cascade regulated by PP2C in poplar. Additionally, PtrHAB2, PtrHAB12, PtrHAB13 and PtrHAB14 interacted with the mitogen-activated protein kinase protein PtrMPK7. Due to its interactions with PtrSnRK2 and PtrMPK7 proteins, and its reduced expression during drought stress, PtrHAB2 was overexpressed in poplar to test its potential as a growth regulator under non-stress conditions. 35S::PtrHAB2 transgenics exhibited increased growth rate for a majority of transgenic events and alterations in leaf phyllotaxy and morphology. These results indicate that PP2Cs have additional roles which extend beyond canonical ABA signaling, possibly coordinating plant growth and development in response to environmental conditions.


Assuntos
Ácido Abscísico/metabolismo , Crescimento e Desenvolvimento/fisiologia , Fosfoproteínas Fosfatases/genética , Fosfoproteínas Fosfatases/metabolismo , Reguladores de Crescimento de Planta/fisiologia , Populus/crescimento & desenvolvimento , Populus/metabolismo , Estresse Fisiológico , Secas , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Crescimento e Desenvolvimento/genética , Fenótipo , Reguladores de Crescimento de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Populus/genética , Proteínas Quinases/genética , Transdução de Sinais , Regulação para Cima
15.
BMC Plant Biol ; 19(1): 99, 2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30866829

RESUMO

BACKGROUND: Adventitious roots (ARs) are roots that are generated from nonrooting tissues. ARs are usually produced both during normal development and in response to stress conditions, such as flooding, nutrient deprivation, heavy metal stress and wounding. The ability of plants to form ARs is a key trait that enables plant propagation, especially for most tree species. RESULTS: Here, the kinetics of AR formation in a tissue culture of a hybrid variety of poplar were investigated. AR formation mainly occurred during the first 8 days and both pre- and newly- formed primordia contributed to AR formation in poplar by histological study. RNA-Seq-based transcriptome analysis was performed for stem bases collected at 0, 2, 4, 6 and 8 days after excision (DAE). Based on the data, the expression patterns of 8 phytohormone-related genes were investigated, and their influences on AR formation were considered. Subsequent gene expression cluster analysis showed a number of biological processes involved in AR formation. Among these biological pathways, genes involved in H2O2 homeostasis showed enrichment in one cluster that was highly upregulated from DAE0 to DAE8. Pharmacological assay confirmed that an appropriate content of H2O2 in stem bases could accelerate the formation of ARs in poplar. CONCLUSIONS: Based on the results of this study, we were able to predict a regulatory network for 7 phytohormones that are involved in poplar AR formation. The influence of H2O2 on AR formation was also confirmed. These results enhance our understanding of the regulation of AR formation in tree species.


Assuntos
Redes Reguladoras de Genes , Peróxido de Hidrogênio/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Populus/genética , Transcriptoma , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Populus/crescimento & desenvolvimento
16.
Int J Mol Sci ; 20(6)2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30875897

RESUMO

Salt stress (SS) has become an important factor limiting afforestation programs. Because of their salt tolerance and fully sequenced genomes, poplars (Populus spp.) are used as model species to study SS mechanisms in trees. Here, we review recent insights into the physiological and molecular responses of Populus to SS, including ion homeostasis and signaling pathways, such as the salt overly sensitive (SOS) and reactive oxygen species (ROS) pathways. We summarize the genes that can be targeted for the genetic improvement of salt tolerance and propose future research areas.


Assuntos
Proteínas de Plantas/genética , Populus/crescimento & desenvolvimento , Estresse Salino , Regulação da Expressão Gênica de Plantas , Homeostase , Populus/efeitos dos fármacos , Populus/genética , Populus/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tolerância ao Sal , Transdução de Sinais
17.
Sci Total Environ ; 665: 929-936, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30893752

RESUMO

Ozone (O3) pollution can alter carbon allocation and reduce tree growth - both above and below ground, but the extent of these effects depends on the variation in soil water and nutrient availability. Here we present the accumulation and allocation of biomass in poplar clone 546 (Populus deltoides cv. '55/56' × P. deltoides cv. 'Imperial') for one growing season at two O3 concentrations (charcoal-filtered air [CF] and non-filtered air + 40 ppb of O3 [E-O3]), two watering regimes (well-watered [WW] and reduced watering at 40% of WW irrigation [RW]) and two soil nitrogen addition treatments (no addition [N0] and the addition of 50 kg N ha-1 year-1 [N50]). We found that the deleterious effects of E-O3 depended on the supply of water and nitrogen. Specifically, when the supplies of water and/or N (WW and/or N50) were abundant, E-O3 significantly reduced whole plant biomass by >15% but had no significant effect on biomass when these supplies were limited (RW and N0). A significant reduction of biomass by E-O3 occurred earlier in fine roots than in other plant organs, indicating greater sensitivity of fine root to E-O3. These results suggest that rising O3 concentrations may not ubiquitously lead to a large reduction in plant biomass since plant growth is often jointly constrained by water and nutrients.


Assuntos
Nitrogênio/análise , Ozônio/metabolismo , Populus/metabolismo , Solo/química , Água/análise , Biomassa , Relação Dose-Resposta a Droga , Ozônio/administração & dosagem , Populus/efeitos dos fármacos , Populus/crescimento & desenvolvimento , Estações do Ano
18.
Ecotoxicol Environ Saf ; 176: 42-49, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30921695

RESUMO

In order to investigate the toxicity-resistance of eighteen Chinese native plants in lead (Pb)-zinc (Zn) mine tailings, we categorized their resistance to Pb and Zn, and tested their potential for phytoremediation effectiveness of Pb and Zn. Fourteen woody plant species belonging to 12 families, and 4 herbaceous species belonging to 4 families, were grown in pots with mixtures of 100% tailing +0% peat (CK), 90% tailing +10% peat (A1), and 80% tailing + 20% peat (A2), respectively. Plant height and biomass, chlorophyll content, and Pb and Zn contents of non-rhizosphere spoil mixtures and plant tissues were measured. Fifteen of the plants grew in all three spoil mixtures. Both A1 and A2 had higher plant height and biomass increment and chlorophyll contents than CK. The content of Pb and Zn in plant shoots and roots was CK > A1 > A2. The value of BCF less than 0.1, compared to 1, was a more precise classification basis for plants excluding metals. Screening for Pb and Zn resistant plants and their bioremediation potential produced the following candidate species: Sapium sebiferum, Salix matsudana, Hibiscus cannabinus, Corchorus capsularis, Ricinus communis, and Populus nigra. These species were highly Pb and Zn tolerant species, with notable growth characteristics and capacities to bioaccumulate Pb and Zn from the mine tailings. Compared to CK, the removal of Pb and Zn from non-rhizosphere spoil increased by an average of 9.64% and 9.6%, respectively in A1, but decreased in A2. The results indicated candidate species and 10% peat addition in the tailing were significant in phytoremediation of Pb and Zn regarding environmental safety.


Assuntos
Biodegradação Ambiental , Chumbo/análise , Desenvolvimento Vegetal/fisiologia , Solo , Zinco/análise , Biomassa , China , Corchorus/crescimento & desenvolvimento , Corchorus/metabolismo , Hibiscus/crescimento & desenvolvimento , Hibiscus/metabolismo , Chumbo/metabolismo , Mineração , Raízes de Plantas/metabolismo , Brotos de Planta/química , Populus/crescimento & desenvolvimento , Populus/metabolismo , Ricinus/crescimento & desenvolvimento , Ricinus/metabolismo , Salix/crescimento & desenvolvimento , Salix/metabolismo , Poluentes do Solo/análise , Madeira/química , Madeira/crescimento & desenvolvimento , Madeira/metabolismo , Zinco/metabolismo
19.
J Environ Manage ; 239: 352-365, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30921754

RESUMO

Phytotechnologies have been used worldwide to remediate and restore damaged ecosystems, especially those caused by industrial byproducts leaching into rivers and other waterways. The objective of this study was to test the growth, physiology, and phytoextraction potential of poplar and willow established in soils amended with heavy-metal contaminated, dredged river sediments from the Great Backa Canal near Vrbas City, Serbia. The sediments were applied to greenhouse-grown trees of Populus deltoides Bartr. ex Marsh. clone 'Bora' and Salix viminalis L. clone 'SV068'. Individual pots with trees previously grown for two months were amended with 0, 0.5 and 1.0 kg of sediment containing 400 mg Cr kg-1, 295 mg Cu kg-1, 465 mg Zn kg-1, 124 mg Ni kg-1, 1.87 mg Cd kg-1, and 61 mg Pb kg-1. Following amendment, trees were grown for two seasons (i.e., 2014, 2015), with coppicing after the first season. In addition to growth parameters, physiological traits related to the photosynthesis and nitrogen metabolism were assessed during both growing seasons. At the end of the study, trees were harvested for biomass analysis and accumulation of heavy metals in tree tissues and soils. Application of sediment decreased aboveground biomass by 37.3% in 2014, but increased height (16.4%) and leaf area (19.2%) in 2015. Sediment application negatively impacted the content of pigments and nitrate reductase activity, causing them to decrease over time. Generally, the effect of treatments on growth was more pronounced in poplars, while willows had more pronounced physiological activity. Accumulation patterns were similar to previously-published results. In particular, Zn and Cd were mostly accumulated in leaves of both poplar and willow, which indicated successful phytoextraction. In contrast, other metals (e.g., Cr, Ni, Pb, Cu) were mostly phytostabilized in the roots. Differences in metal allocation between poplar and willow were recorded only for Cu, while other metals followed similar distribution patterns in both genera. Results of this study indicated that the composition of heavy metals in the sediments determined the mechanisms of the applied phytoremediation technique.


Assuntos
Metais Pesados/análise , Populus/química , Populus/crescimento & desenvolvimento , Rios/química , Salix/química , Salix/crescimento & desenvolvimento , Solo/química , Biomassa , Sedimentos Geológicos/química , Fotossíntese , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Populus/metabolismo , Salix/metabolismo , Sérvia , Poluentes do Solo/análise , Árvores/química , Árvores/metabolismo
20.
Plant Cell ; 31(3): 602-626, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30755461

RESUMO

Wood remains the world's most abundant and renewable resource for timber and pulp and is an alternative to fossil fuels. Understanding the molecular regulation of wood formation can advance the engineering of wood for more efficient material and energy productions. We integrated a black cottonwood (Populus trichocarpa) wood-forming cell system with quantitative transcriptomics and chromatin binding assays to construct a transcriptional regulatory network (TRN) directed by a key transcription factor (TF), PtrSND1-B1 (secondary wall-associated NAC-domain protein). The network consists of four layers of TF-target gene interactions with quantitative regulatory effects, describing the specificity of how the regulation is transduced through these interactions to activate cell wall genes (effector genes) for wood formation. PtrSND1-B1 directs 57 TF-DNA interactions through 17 TFs transregulating 27 effector genes. Of the 57 interactions, 55 are novel. We tested 42 of these 57 interactions in 30 genotypes of transgenic P. trichocarpa and verified that ∼90% of the tested interactions function in vivo. The TRN reveals common transregulatory targets for distinct TFs, leading to the discovery of nine TF protein complexes (dimers and trimers) implicated in regulating the biosynthesis of specific types of lignin. Our work suggests that wood formation may involve regulatory homeostasis determined by combinations of TF-DNA and TF-TF (protein-protein) regulations.


Assuntos
Cromatina/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Redes Reguladoras de Genes/genética , Populus/genética , Fatores de Transcrição/metabolismo , Parede Celular/metabolismo , Cromatina/genética , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Populus/fisiologia , Fatores de Transcrição/genética , Madeira/crescimento & desenvolvimento
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