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1.
BMC Plant Biol ; 21(1): 405, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34488640

RESUMO

BACKGROUND: Clones provide a sensitive method for evaluating genotypic stability and detecting genotype-environment (G × E) interactions because of non-additive genetic effects among clones and there being no genetic effect among ramets of an ortet. With this study, we aimed to confirm and expand earlier findings, estimate stability parameters, and provide accurate estimates of clonal repeatabilities and genetic gains for a triploid breeding program of P. tomentosa Carr. RESULTS: Six 5-year-old clonal trials established in Northern China were used to determine the clonal variation, clone × site interactions, and the stability parameters of fiber properties of wood and growth traits. 360 trees from ten hybrid clones were collected from six sites. The clonal and site effects had a highly significant effect (P < 0.001) for all studied traits. While the clone × site interactions had a highly significant effect (P < 0.001) on fiber length (FL), coarseness (C), and tree growth (tree height [H], diameter at breast height [DBH] and stem volume [SV]), and a moderate effect (P < 0.05) on fiber width (FW) and fiber length/width (FL/W). For FL and SV, most of the triploid hybrid clones had higher reaction norms to the improvement in growth conditions and higher phenotypic plasticity. The estimated clonal repeatability of FW (0.93) was slightly higher than for FL (0.89), FL/W (0.83), C (0.91), DBH (0.76), H (0.85), and SV (0.80). Three clonal testing sites were sufficient to estimate quantitative parameters of fiber properties, however, more clonal testing sites would help improve the accuracy of quantitative parameters of the growth traits. CONCLUSIONS: Our results highlight that accurate estimation of quantitative parameters for growth traits in triploid hybrid clones of P. tomentosa requires more clonal testing sites than the fiber properties.


Assuntos
Clonagem de Organismos , Genótipo , Populus/crescimento & desenvolvimento , Populus/genética , Triploidia , Madeira , Interação Gene-Ambiente , Variação Genética , Melhoramento Vegetal/métodos
2.
Int J Mol Sci ; 22(18)2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34576062

RESUMO

Drought is a severe environmental stress that exerts negative effects on plant growth. In trees, drought leads to reduced secondary growth and altered wood anatomy. The mechanisms underlying wood stress adaptation are not well understood. Here, we investigated the physiological, anatomical, hormonal, and transcriptional responses of poplar to strong drought. Drought-stressed xylem was characterized by higher vessel frequencies, smaller vessel lumina, and thicker secondary fiber cell walls. These changes were accompanied by strong increases in abscisic acid (ABA) and antagonistic changes in salicylic acid in wood. Transcriptional evidence supported ABA biosynthesis and signaling in wood. Since ABA signaling activates the fiber-thickening factor NST1, we expected upregulation of the secondary cell wall (SCW) cascade under stress. By contrast, transcription factors and biosynthesis genes for SCW formation were down-regulated, whereas a small set of cellulose synthase-like genes and a huge array of genes involved in cell wall modification were up-regulated in drought-stressed wood. Therefore, we suggest that ABA signaling monitors normal SCW biosynthesis and that drought causes a switch from normal to "stress wood" formation recruiting a dedicated set of genes for cell wall biosynthesis and remodeling. This proposition implies that drought-induced changes in cell wall properties underlie regulatory mechanisms distinct from those of normal wood.


Assuntos
Reguladores de Crescimento de Plantas/genética , Populus/genética , Transcrição Genética , Madeira/genética , Parede Celular/genética , Secas , Regulação da Expressão Gênica de Plantas/genética , Populus/crescimento & desenvolvimento , Estresse Fisiológico/genética , Ativação Transcricional/genética , Madeira/crescimento & desenvolvimento , Xilema/genética , Xilema/crescimento & desenvolvimento
3.
Plant Sci ; 311: 111021, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34482922

RESUMO

HD-Zip is a plant-specific HB transcription factor, which participates in plant development and stress response. In this study, we identified 63 poplar HD-Zip transcription factors, which were randomly distributed on 19 chromosomes of poplar. Based on the gene structure and phylogenetic relationship, these members are divided into four groups, which have a variety of collinear evolutionary relationships. They also have rich segmental replication events and experienced strong purification selection. Based on RNA-seq analysis, we profiled the expression pattern of the 63 HD-Zip members under salt stress. Subsequently, we carried out in-depth study on the significantly up-regulated PsnHDZ63 in the stems and leaves. The transgenic Populus simonii × P.nigra plants over-expressing PsnHDZ63 displayed better morphological and physiological indexes than WT under salt stress. In addition, PsnHDZ63 enhanced salt stress tolerance of transgenic lines by combining effective stress-resistant elements to improve reactive oxygen species scavenging ability. These studies laid a foundation for a comprehensive understanding of poplar HD-Zip family members, and revealed the important role of PsnHDZ63 in plant salt tolerance.


Assuntos
Arabidopsis/genética , Plantas Geneticamente Modificadas/fisiologia , Populus/crescimento & desenvolvimento , Populus/genética , Tolerância ao Sal/genética , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Estudo de Associação Genômica Ampla , Genótipo , Análise de Sequência de Proteína
4.
Cells ; 10(8)2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34440740

RESUMO

Secondary growth relies on precise and specialized transcriptional networks that determine cell division, differentiation, and maturation of xylem cells. We identified a novel role for the ethylene-induced Populus Ethylene Response Factor PtERF85 (Potri.015G023200) in balancing xylem cell expansion and secondary cell wall (SCW) formation in hybrid aspen (Populus tremula x tremuloides). Expression of PtERF85 is high in phloem and cambium cells and during the expansion of xylem cells, while it is low in maturing xylem tissue. Extending PtERF85 expression into SCW forming zones of woody tissues through ectopic expression reduced wood density and SCW thickness of xylem fibers but increased fiber diameter. Xylem transcriptomes from the transgenic trees revealed transcriptional induction of genes involved in cell expansion, translation, and growth. The expression of genes associated with plant vascular development and the biosynthesis of SCW chemical components such as xylan and lignin, was down-regulated in the transgenic trees. Our results suggest that PtERF85 activates genes related to xylem cell expansion, while preventing transcriptional activation of genes related to SCW formation. The importance of precise spatial expression of PtERF85 during wood development together with the observed phenotypes in response to ectopic PtERF85 expression suggests that PtERF85 contributes to the transition of fiber cells from elongation to secondary cell wall deposition.


Assuntos
Parede Celular/metabolismo , Proteínas de Plantas/metabolismo , Populus/metabolismo , Xilema/metabolismo , Câmbio/metabolismo , Parede Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Etilenos/farmacologia , Redes Reguladoras de Genes , Lignina/metabolismo , Floema/metabolismo , Filogenia , Proteínas de Plantas/classificação , Proteínas de Plantas/genética , Populus/crescimento & desenvolvimento , Regulação para Cima/efeitos dos fármacos , Madeira/crescimento & desenvolvimento , Madeira/metabolismo , Xilema/citologia , Xilema/efeitos dos fármacos
5.
Physiol Plant ; 173(3): 1008-1029, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34272872

RESUMO

Plant metabolic acclimation to thermal stress remains underrepresented in current global climate models. Gaps exist in our understanding of how metabolic processes (i.e., photosynthesis, respiration) acclimate over time and how aboveground versus belowground acclimation differs. We measured the thermal acclimation of Populus trichocarpa, comparing aboveground versus belowground physiology over time. Ninety genetically identical ramets were propagated in mesocosms that separated root and microbial components. After establishment at 25°C for 6 weeks, 60 clones were warmed +4 or +8°C and monitored for 10 weeks, measuring photosynthesis (A), leaf respiration (R), soil respiration (Rs ), root plus soil respiration (Rs+r ), and root respiration (Rr ). We observed thermal acclimation in both A and R, with rates initially increasing, then declining as the thermal photosynthetic optimum (Topt ) and the temperature-sensitivity (Q10 ) of respiration adjusted to warmer conditions. Photosynthetic acclimation was constructive, based on an increase in both Topt and peak A. Belowground, Rs+r decreased linearly with warming, while Rs rates declined abruptly, then remained constant with additional warming. Plant biomass was greatest at +4°C, with 30% allocated belowground. Rates of mass-based Rr were similar among treatments; however, root nitrogen declined at +8°C leading to less mass nitrogen-based Rr in that treatment. The Q10 -temperature relationship of Rr was affected by warming, leading to differing values among treatments. Aboveground acclimation exceeded belowground acclimation, and plant nitrogen-use mediated the acclimatory response. Results suggest that moderate climate warming (+4°C) may lead to acclimation and increased plant biomass production but increases in production could be limited with severe warming (+8°C).


Assuntos
Aclimatação , Aquecimento Global , Populus , Clima , Fotossíntese , Folhas de Planta , Populus/crescimento & desenvolvimento , Temperatura
6.
Methods Mol Biol ; 2317: 257-265, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34028774

RESUMO

Poplar (Populus) is an important forest tree and considered model for perennial trees. Here we describe a method for poplar plastid transformation, which involves preparation of explants, vector construction, biolistic bombardment, regeneration and selection of transplastomic poplar plants. The young leaves of 4-week-old poplar plants are used for biolistic bombardment and aadA gene as selectable marker. Homoplasmic transplastomic lines are obtained after regeneration and several rounds of selection with spectinomycin over 10 months. Homoplasmy is further confirmed by Southern blot. The establishment of a plastid transformation system for Populus is likely to make a significant contribution to tree genetic improvement.


Assuntos
Genes de Plantas , Engenharia Genética/métodos , Plantas Geneticamente Modificadas/genética , Plastídeos/genética , Populus/genética , Transformação Genética , Árvores/genética , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Populus/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento
7.
Int J Mol Sci ; 22(9)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33925110

RESUMO

Poplar are planted extensively in reforestation and afforestation. However, their successful establishment largely depends on the environmental conditions of the newly established plantation and their resistance to abiotic as well as biotic stresses. NF-X1, a widespread transcription factor in plants, plays an irreplaceable role in plant growth, development, and stress tolerance. Although the whole genome sequence of Populus trichocarpa has been published for a long time, little is known about the NF-X1 genes in poplar, especially those related to drought stress, mechanical damage, insect feeding, and hormone response at the whole genome level. In this study, whole genome analysis of the poplar NF-X1 family was performed, and 4 PtrNF-X1 genes were identified. Then, bioinformatics analysis and qRT-PCR were applied to analyze the gene structure, phylogeny, chromosomal localization, gene replication, Cis-elements, and expression patterns of PtrNF-X1genes. Sequence analysis revealed that one-quarter of the PtrNF-X1 genes did not contain introns. Phylogenetic analysis revealed that all NF-X1 genes were split into three subfamilies. The number of two pairs of segmented replication genes were detected in poplars. Cis-acting element analysis identified a large number of elements of growth and development and stress-related elements on the promoters of different NF-X1 members. In addition, some PtrNF-X1 could be significantly induced by polyethylene glycol (PEG) and abscisic acid (ABA), thus revealing their potential role in regulating stress response. Comprehensive analysis is helpful in selecting candidate NF-X1 genes for the follow-up study of the biological function, and molecular genetic progress of stress resistance in forest trees provides genetic resources.


Assuntos
Genes de Plantas , Proteínas de Plantas/genética , Populus/genética , Fatores de Transcrição/genética , Arabidopsis/genética , Cromossomos de Plantas/genética , Evolução Molecular , Duplicação Gênica , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Família Multigênica , Oryza/genética , Filogenia , Populus/crescimento & desenvolvimento , Especificidade da Espécie , Estresse Fisiológico/genética , Sintenia
8.
PLoS One ; 16(4): e0250078, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33831122

RESUMO

Over the past several decades, growth declines and mortality of trembling aspen throughout western Canada and the United States have been linked to drought, often interacting with outbreaks of insects and fungal pathogens, resulting in a "sudden aspen decline" throughout much of aspen's range. In 2015, we noticed an aggressive fungal canker causing widespread mortality of aspen throughout interior Alaska and initiated a study to quantify potential drivers for the incidence, virulence, and distribution of the disease. Stand-level infection rates among 88 study sites distributed across 6 Alaska ecoregions ranged from <1 to 69%, with the proportion of trees with canker that were dead averaging 70% across all sites. The disease is most prevalent north of the Alaska Range within the Tanana Kuskokwim ecoregion. Modeling canker probability as a function of ecoregion, stand structure, landscape position, and climate revealed that smaller-diameter trees in older stands with greater aspen basal area have the highest canker incidence and mortality, while younger trees in younger stands appear virtually immune to the disease. Sites with higher summer vapor pressure deficits had significantly higher levels of canker infection and mortality. We believe the combined effects of this novel fungal canker pathogen, drought, and the persistent aspen leaf miner outbreak are triggering feedbacks between carbon starvation and hydraulic failure that are ultimately driving widespread mortality. Warmer early-season temperatures and prolonged late summer drought are leading to larger and more severe wildfires throughout interior Alaska that are favoring a shift from black spruce to forests dominated by Alaska paper birch and aspen. Widespread aspen mortality fostered by this rapidly spreading pathogen has significant implications for successional dynamics, ecosystem function, and feedbacks to disturbance regimes, particularly on sites too dry for Alaska paper birch.


Assuntos
Micoses/epidemiologia , Populus/crescimento & desenvolvimento , Populus/microbiologia , Alaska , Mudança Climática , Secas , Ecossistema , Florestas , Fungos/patogenicidade , Micoses/fisiopatologia , Doenças das Plantas/etiologia , Populus/metabolismo , Estações do Ano , Temperatura
9.
Microbiol Res ; 248: 126767, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33873138

RESUMO

Xylanase secreted by Trichoderma asperellum ACCC30536 can stimulate the systemic resistance of host plants against pathogenic fungi. Following T. asperellum conidia co-culture with Populus davidiana × P. alba var. pyramidalis Louche (PdPap) seedlings, the expression of xylanases TasXyn29.4 and TasXyn24.2 in T. asperellum were upregulated, peaking at 12 h, by 106 (26.74) and 10.1 (23.34)-fold compared with the control, respectively. However, the expression of TasXyn24.4 and TasXyn24.0 was not detected. When recombinant xylanases rTasXyn29.4 and rTasXyn24.2 were heterologously expressed in Pichia pastoris GS115, their activities reached 18.9 IU/mL and 20.4 IU/mL, respectively. In PdPap seedlings induced by rTasXyn29.4 and rTasXyn24.2, the auxin and jasmonic acid signaling pathways were activated to promote growth and enhance resistance against pathogens. PdPap seedlings treated with both xylanases showed increased methyl jasmonate contents at 12 hpi, reaching 122 % (127 µg/g) compared with the control. However, neither of the xylanases could induce the salicylic acid signaling pathway in PdPap seedlings. Meanwhile, both xylanases could enhance the antioxidant ability of PdPap seedlings by improving their catalase activity. Both xylanases significantly induced systemic resistance of PdPap seedlings against Alternaria alternata, Rhizoctonia solani, and Fusarium oxysporum. However, the xylanases could only be sensed by the roots of the PdPap seedlings, not the leaves. In summary, rTasXyn29.4 and rTasXyn24.2 from T. asperellum ACCC30536 promoted growth and induced systemic resistance of PdPap seedlings, which endowed the PdPap seedlings broad-spectrum resistance to phytopathogens.


Assuntos
Endo-1,4-beta-Xilanases/farmacologia , Proteínas Fúngicas/farmacologia , Hypocreales/enzimologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/farmacologia , Populus/crescimento & desenvolvimento , Alternaria/fisiologia , Ciclopentanos/imunologia , Resistência à Doença , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fusarium/fisiologia , Regulação Fúngica da Expressão Gênica , Hypocreales/química , Hypocreales/genética , Ácidos Indolacéticos/imunologia , Oxilipinas/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/efeitos dos fármacos , Populus/imunologia , Populus/microbiologia , Rhizoctonia/fisiologia
10.
Plant Cell ; 33(5): 1594-1614, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-33793897

RESUMO

During leaf senescence, the final stage of leaf development, nutrients are recycled from leaves to other organs, and therefore proper control of senescence is thus critical for plant fitness. Although substantial progress has been achieved in understanding leaf senescence in annual plants, the molecular factors that control leaf senescence in perennial woody plants are largely unknown. Using RNA sequencing, we obtained a high-resolution temporal profile of gene expression during autumn leaf senescence in poplar (Populus tomentosa). Identification of hub transcription factors (TFs) by co-expression network analysis of genes revealed that senescence-associated NAC family TFs (Sen-NAC TFs) regulate autumn leaf senescence. Age-dependent alternative splicing (AS) caused an intron retention (IR) event in the pre-mRNA encoding PtRD26, a NAC-TF. This produced a truncated protein PtRD26IR, which functions as a dominant-negative regulator of senescence by interacting with multiple hub Sen-NAC TFs, thereby repressing their DNA-binding activities. Functional analysis of senescence-associated splicing factors identified two U2 auxiliary factors that are involved in AS of PtRD26IR. Correspondingly, silencing of these factors decreased PtRD26IR transcript abundance and induced early senescence. We propose that an age-dependent increase of IR splice variants derived from Sen-NAC TFs is a regulatory program to fine tune the molecular mechanisms that regulate leaf senescence in trees.


Assuntos
Processamento Alternativo/genética , Folhas de Planta/genética , Proteínas de Plantas/genética , Populus/genética , Fatores de Transcrição/genética , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Modelos Biológicos , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Ligação Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Estações do Ano , Fatores de Tempo , Fatores de Transcrição/metabolismo
11.
Int J Mol Sci ; 22(5)2021 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-33673666

RESUMO

Chlorogenic acid (CGA) plays a crucial role in defense response, immune regulation, and the response to abiotic stress in plants. However, the genetic regulatory network of CGA biosynthesis pathways in perennial plants remains unclear. Here, we investigated the genetic architecture for CGA biosynthesis using a metabolite-based genome-wide association study (mGWAS) and expression quantitative trait nucleotide (eQTN) mapping in a population of 300 accessions of Populus tomentosa. In total, we investigated 204 SNPs which were significantly associated with 11 metabolic traits, corresponding to 206 genes, and were mainly involved in metabolism and cell growth processes of P. tomentosa. We identified 874 eQTNs representing 1066 genes, in which the expression and interaction of causal genes affected phenotypic variation. Of these, 102 genes showed significant signatures of selection in three geographical populations, which provided insights into the adaptation of CGA biosynthesis to the local environment. Finally, we constructed a genetic network of six causal genes that coordinately regulate CGA biosynthesis, revealing the multiple regulatory patterns affecting CGA accumulation in P. tomentosa. Our study provides a multiomics strategy for understanding the genetic basis underlying the natural variation in the CGA biosynthetic metabolites of Populus, which will enhance the genetic development of abiotic-resistance varieties in forest trees.


Assuntos
Ácido Clorogênico/metabolismo , Redes Reguladoras de Genes , Metaboloma , Proteínas de Plantas/metabolismo , Polimorfismo de Nucleotídeo Único , Populus/metabolismo , Locos de Características Quantitativas , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Estudo de Associação Genômica Ampla , Fenótipo , Proteínas de Plantas/genética , Populus/genética , Populus/crescimento & desenvolvimento
12.
Plant Sci ; 305: 110832, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33691966

RESUMO

Intercellular communication mediated by the plant-specific CLAVATA3/ENDOSPERM SURROUNDING REGION (ESR)-related (CLE) family members is one of the fundamental mechanisms coordinating the development of complex bodies of plants. In this work, we chose 8 out of 38 putative CLE dodecapeptides encoded in the genome of P. trichocarpa based on their lowest sequence similarity with Arabidopsis CLE peptides, and investigated how such sequence variations affect their functional characteristics. In group 1, PtCLE16p faithfully retained the AtCLE1-7p activity, while PtCLE49p reversed the root-enhancing effect to an inhibitory one with two extra amino acid substitutions, which might have disrupted the capacity of PtCLE49p to recognize the corresponding receptors. In group 2, PtCLE9p conferred Arabidopsis with retarded root growth and suppressed phloem differentiation in a negative dominant manner just like AtCLE25G6T did. PtCLE9p enhanced the vegetative growth in both basal and aerial rosettes by regulating the expression of AERIAL ROSETTE 1 (ART1) and FRIGIDA (FRI) as well as the downstream FLOWERING LOCUS C (FLC) genes. In group 3, PtCLE34p and PtCLE5p slightly promoted primary root growth, while PtCLE40p revealed CLV3p-like and TDIF activity in root and hypocotyls, respectively. The remaining PtCLE18p in group 4 dramatically disturbed the expression of WOX5 and promoted the development of root hairs by repressing the expression of GLABRA2 (GL2) gene, which encoded a negative regulator of epidermal cells differentiation towards root hairs. In summary, our data indicated that with significant functional conservation and common signaling machinery existing for CLE families of land plants, unique and diverse activities of CLE peptides have evolved to perform specific functions in different plant species.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , Arabidopsis/metabolismo , Meristema/genética , Peptídeos/metabolismo , Populus/crescimento & desenvolvimento , Populus/genética , Populus/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo
13.
PLoS One ; 16(2): e0232995, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33539349

RESUMO

Quaking aspen (Populus tremuloides) is a valued, minor component on northeastern California landscapes. It provides a wide range of ecosystem services and has been in decline throughout the region for the last century. This decline may be explained partially by the lack of fire on the landscape due to heavier fire suppression, as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. However, there is little known about how aspen stand area changes in response to overlapping fire. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has experienced recent large mixed-severity wildfires where aspen was present, providing an opportunity to study the re-introduction of fire. We observed two time periods; a 52-year absence of fire from 1941 to 1993 preceding a 24-year period of wildfire activity from 1993 to 2017. We utilized aerial photos and satellite imagery to delineate aspen stands and assess conifer cover percent. We chose aspen stands in areas where wildfires overlapped (twice-burned), where only a single wildfire burned, and areas that did not burn within the recent 24-year period. We observed these same stands within the first period of fire exclusion for comparison (i.e., 1941-1993). In the absence of fire, all aspen stand areas declined and all stands experienced increases in conifer composition. After wildfire, stands that burned experienced a release from conifer competition and increased in stand area. Stands that burned twice or at high severity experienced a larger removal of conifer competition than stands that burned once at low severity, promoting expansion of aspen stand area. Stands with less edge:area ratio also expanded in area more with fire present. Across both time periods, stand movement, where aspen stand footprints were mostly in new areas compared to footprints of previous years, was highest in smaller stands. In the fire exclusion period, smaller stands exhibited greater loss of area and changes in location (movement) than in the return of fire period, highlighting their vulnerability to loss via succession to conifers in the absence of disturbances that provide adequate growing space for aspen over time.


Assuntos
Populus/crescimento & desenvolvimento , Ecossistema , Incêndios , Florestas , Imagens de Satélites/métodos , Traqueófitas/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Incêndios Florestais
14.
Int J Mol Sci ; 22(3)2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33525476

RESUMO

D-type cyclin (cyclin D, CYCD), combined with cyclin-dependent kinases (CDKs), participates in the regulation of cell cycle G1/S transition and plays an important role in cell division and proliferation. CYCD could affect the growth and development of herbaceous plants, such as Arabidopsis thaliana, by regulating the cell cycle process. However, its research in wood plants (e.g., poplar) is poor. Phylogenetic analysis showed that in Populus trichocarpa, CYCD3 genes expanded to six members, namely PtCYCD3;1-6. P. tomentosa CYCD3 genes were amplified based on the CDS region of P. trichocarpa CYCD3 genes. PtoCYCD3;3 showed the highest expression in the shoot tip, and the higher expression in young leaves among all members. Therefore, this gene was selected for further study. The overexpression of PtoCYCD3;3 in plants demonstrated obvious morphological changes during the observation period. The leaves became enlarged and wrinkled, the stems thickened and elongated, and multiple branches were formed by the plants. Anatomical study showed that in addition to promoting the differentiation of cambium tissues and the expansion of stem vessel cells, PtoCYCD3;3 facilitated the division of leaf adaxial epidermal cells and palisade tissue cells. Yeast two-hybrid experiment exhibited that 12 PtoCDK proteins could interact with PtoCYCD3;3, of which the strongest interaction strength was PtoCDKE;2, whereas the weakest was PtoCDKG;3. Molecular docking experiments further verified the force strength of PtoCDKE;2 and PtoCDKG;3 with PtoCYCD3;3. In summary, these results indicated that the overexpression of PtoCYCD3;3 significantly promoted the vegetative growth of Populus, and PtoCYCD3;3 may interact with different types of CDK proteins to regulate cell cycle processes.


Assuntos
Ciclina D3/genética , Ciclina D3/metabolismo , Populus/anatomia & histologia , Populus/crescimento & desenvolvimento , Ciclo Celular , Ciclina D3/química , Quinases Ciclina-Dependentes/química , Quinases Ciclina-Dependentes/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Modelos Moleculares , Família Multigênica , Filogenia , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/genética , Populus/metabolismo , Conformação Proteica , Distribuição Tecidual
15.
Nat Commun ; 12(1): 1123, 2021 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602938

RESUMO

Bud-break is an economically and environmentally important process in trees and shrubs from boreal and temperate latitudes, but its molecular mechanisms are poorly understood. Here, we show that two previously reported transcription factors, EARLY BUD BREAK 1 (EBB1) and SHORT VEGETATIVE PHASE-Like (SVL) directly interact to control bud-break. EBB1 is a positive regulator of bud-break, whereas SVL is a negative regulator of bud-break. EBB1 directly and negatively regulates SVL expression. We further report the identification and characterization of the EBB3 gene. EBB3 is a temperature-responsive, epigenetically-regulated, positive regulator of bud-break that provides a direct link to activation of the cell cycle during bud-break. EBB3 is an AP2/ERF transcription factor that positively and directly regulates CYCLIND3.1 gene. Our results reveal the architecture of a putative regulatory module that links temperature-mediated control of bud-break with activation of cell cycle.


Assuntos
Dormência de Plantas/fisiologia , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Populus/metabolismo , Estações do Ano , Ácido Abscísico/metabolismo , Epigênese Genética , Flores/fisiologia , Regulação da Expressão Gênica de Plantas , Modelos Biológicos , Mutação/genética , Fenótipo , Proteínas de Plantas/genética , Populus/genética , Regiões Promotoras Genéticas/genética , Transcriptoma/genética
16.
BMC Plant Biol ; 21(1): 111, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33627081

RESUMO

BACKGROUND: Over the life cycle of perennial trees, the dormant state enables the avoidance of abiotic stress conditions. The growth cycle can be partitioned into induction, maintenance and release and is controlled by complex interactions between many endogenous and environmental factors. While phytohormones have long been linked with dormancy, there is increasing evidence of regulation by DAM and CBF genes. To reveal whether the expression kinetics of CBFs and their target PtDAM1 is related to growth cessation and endodormancy induction in Populus, two hybrid poplar cultivars were studied which had known differential responses to dormancy inducing conditions. RESULTS: Growth cessation, dormancy status and expression of six PtCBFs and PtDAM1 were analyzed. The 'Okanese' hybrid cultivar ceased growth rapidly, was able to reach endodormancy, and exhibited a significant increase of several PtCBF transcripts in the buds on the 10th day. The 'Walker' cultivar had delayed growth cessation, was unable to enter endodormancy, and showed much lower CBF expression in buds. Expression of PtDAM1 peaked on the 10th day only in the buds of 'Okanese'. In addition, PtDAM1 was not expressed in the leaves of either cultivar while leaf CBFs expression pattern was several fold higher in 'Walker', peaking at day 1. Leaf phytohormones in both cultivars followed similar profiles during growth cessation but differentiated based on cytokinins which were largely reduced, while the Ox-IAA and iP7G increased in 'Okanese' compared to 'Walker'. Surprisingly, ABA concentration was reduced in leaves of both cultivars. However, the metabolic deactivation product of ABA, phaseic acid, exhibited an early peak on the first day in 'Okanese'. CONCLUSIONS: Our results indicate that PtCBFs and PtDAM1 have differential kinetics and spatial localization which may be related to early growth cessation and endodormancy induction under the regime of low night temperature and short photoperiod in poplar. Unlike buds, PtCBFs and PtDAM1 expression levels in leaves were not associated with early growth cessation and dormancy induction under these conditions. Our study provides new evidence that the degradation of auxin and cytokinins in leaves may be an important regulatory point in a CBF-DAM induced endodormancy. Further investigation of other PtDAMs in bud tissue and a study of both growth-inhibiting and the degradation of growth-promoting phytohormones is warranted.


Assuntos
Quimera/crescimento & desenvolvimento , Desenvolvimento Vegetal/genética , Dormência de Plantas/genética , Reguladores de Crescimento de Plantas/genética , Populus/crescimento & desenvolvimento , Populus/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética
17.
BMC Plant Biol ; 21(1): 110, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33627082

RESUMO

BACKGROUND: The Late Embryogenesis-Abundant (LEA) gene families, which play significant roles in regulation of tolerance to abiotic stresses, widely exist in higher plants. Poplar is a tree species that has important ecological and economic values. But systematic studies on the gene family have not been reported yet in poplar. RESULTS: On the basis of genome-wide search, we identified 88 LEA genes from Populus trichocarpa and renamed them as PtrLEA. The PtrLEA genes have fewer introns, and their promoters contain more cis-regulatory elements related to abiotic stress tolerance. Our results from comparative genomics indicated that the PtrLEA genes are conserved and homologous to related genes in other species, such as Eucalyptus robusta, Solanum lycopersicum and Arabidopsis. Using RNA-Seq data collected from poplar under two conditions (with and without salt treatment), we detected 24, 22 and 19 differentially expressed genes (DEGs) in roots, stems and leaves, respectively. Then we performed spatiotemporal expression analysis of the four up-regulated DEGs shared by the tissues, constructed gene co-expression-based networks, and investigated gene function annotations. CONCLUSION: Lines of evidence indicated that the PtrLEA genes play significant roles in poplar growth and development, as well as in responses to salt stress.


Assuntos
Mapeamento Cromossômico , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Populus/genética , Estresse Fisiológico/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genoma de Planta , Estudo de Associação Genômica Ampla , Família Multigênica
18.
Ecotoxicol Environ Saf ; 208: 111688, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396020

RESUMO

Elemental defense hypothesis suggests that toxic metals accumulated in plant tissues could enhance plant defense against herbivores and pathogens. Since over-accumulation of metals in plant organs will pose negative effects on plant health, it is necessary to find a way to alleviate metal-induced toxicity in plants while keeping or even improving plant resistance. Exogenous nitrogen (N) application was reported to have such alleviation effect while stimulating metal accumulation in plant tissues. In this study, we examined whether soil N addition in three different doses to a poplar species under cadmium (Cd) stress can simultaneously improve plant growth and resistance to four herbivorous insects and a leaf pathogen. The results showed that N application to Cd-amended soil prominently enhanced plant growth and leaf Cd accumulation. While N addition in three doses all remarkably reduced herbivore growth than control plants, only the highest N dose exerted stronger inhibition than the sole Cd-treated plants. In the paired-choice experiment, plants supplied with the highest N dose showed an enhanced deterrent effect on herbivore preference than plants exposed to sole Cd. Furthermore, plant resistance to the leaf pathogen infection was strongly enhanced as the levels of N addition increased. Leaf sugar and three main defensive chemicals were not affected by N application implied that such enhanced effect of N on plant resistance was due to increased leaf Cd accumulation. Our results suggested that the application of exogenous N over a certain amount could enhance the resistance of Cd-treated plants to leaf herbivory and pathogen infection.


Assuntos
Cádmio/toxicidade , Nitrogênio/farmacologia , Folhas de Planta/efeitos dos fármacos , Populus/efeitos dos fármacos , Poluentes do Solo/toxicidade , Animais , Cádmio/metabolismo , Herbivoria/efeitos dos fármacos , Lepidópteros/efeitos dos fármacos , Pestalotiopsis/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Populus/crescimento & desenvolvimento , Populus/microbiologia , Solo/química , Poluentes do Solo/metabolismo
19.
Gene ; 772: 145349, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33338511

RESUMO

Inverted cuttings of Populus yunnanensis are characterized by enlarged stems and dwarfed new shoots, and phytohormones play a crucial role in the response to inversion. The polar auxin transport (PAT) system is distinct from the transport systems of other hormones and is controlled by three major transporter gene families: pin-formed (PIN), auxin-resistant/like aux (AUX/LAX) and ATP-binding cassette transporters of the B class (ABCB). Here, we identified these three families in P. trichocarpa, P. euphratica and P. yunnanensis through a genome-wide analysis. The Populus PIN, AUX/LAX and ABCB gene families comprised 15, 8 and 31 members, respectively. Most PAT genes in Populus and Arabidopsis were identified as clear sister pairs, and some had unique motifs. Transcriptome profiling revealed that the expression of most PAT genes was unrelated to cutting inversion and that only several genes showed altered expression when cuttings were inverted. The auxin content difference at positions was opposite in upright and inverted cutting bodies during rooting, which obeyed the original plant polarity. However, during plant growth, the two direction types exhibited similar auxin movements in the cutting bodies, and the opposite auxin changes were observed in new shoots. Four PAT genes with a positive response to cutting inversion, PyuPIN10, PyuPIN11, PyuLAX6 and PyuABCB27, showed diverse expression patterns between upright and inverted cuttings during rooting and plant growth. Furthermore, PAT gene expression retained its polarity, which differs from the results found for auxin flow during plant growth. The inconformity indicated that a new downward auxin flow in addition to the old upward flow might be established during the growth of inverted cuttings. Some highly polar PAT genes were involved in the maintenance of original auxin polarity, which might cause the enlarged stems of inverted cuttings. This work lays a foundation for understanding the roles of auxin transport in plant responses to inversion.


Assuntos
Perfilação da Expressão Gênica/métodos , Ácidos Indolacéticos/metabolismo , Proteínas de Membrana Transportadoras/genética , Populus/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/metabolismo , Família Multigênica , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/classificação , Populus/genética , Populus/metabolismo , Sequenciamento Completo do Genoma
20.
Genes (Basel) ; 11(12)2020 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-33261043

RESUMO

Tetraploid plants often have altered rates of vegetative growth relative to their diploid progenitors. However, the molecular basis for altered growth rates remains a mystery. This study reports microRNA (miRNA) and gene expression differences in Populus tetraploids and counterpart diploids using RNA and miRNA sequencing. The results showed that there was no significant difference between young leaves in the expression of vegetative growth-related miRNAs. However, as leaves aged, the expression of auxin- and gibberellin-related miRNAs was significantly upregulated, while the expression of senescence-related miRNAs was significantly downregulated. The dose effect enhanced the negative regulation of the target genes with ARFs, GA20ox, GA3ox, and GAMYB being downregulated, and TCP and NAC being upregulated. As a result, the chloroplast degradation of tetraploid leaves was accelerated, the photosynthetic rate was decreased, and the synthesis and decomposition ability of carbohydrate was decreased.


Assuntos
Populus/genética , Tetraploidia , Proteínas CLOCK/genética , Clorofila/análise , Cloroplastos/metabolismo , Diploide , Dosagem de Genes , Duplicação Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genótipo , MicroRNAs/genética , Fotossíntese , Reguladores de Crescimento de Plantas/fisiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Populus/crescimento & desenvolvimento , Populus/metabolismo , RNA de Plantas/genética , Transdução de Sinais , Amido/análise , Açúcares/análise , Transcriptoma
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