We investigated feasibility of the Full-length complementary DNA OvereXpression (FOX) system as a mutagenesis approach in poplar, using developing xylem tissue. The main goal was to assess the overall mutation rate and if the system will increase instances of mutants affected in traits linked to the xylem tissue. Indeed, we found a high mutation rate of 17.7%, whereas 80% of all mutants were significantly affected in cellulose, lignin and/or hemicellulose. Cell wall biosynthesis is a major process occurring during xylem development. Enrichment of mutants affected in cell wall composition suggests that the tissue source for the FOX library influenced the occurrence of mutants affected in a trait linked to this tissue. Additionally, we found that FLcDNAs from mutants affected in cell wall composition were homologous to genes known to be involved in cell wall biosynthesis and most recovered FLcDNAs corresponded to genes whose native expression was highest in xylem. We characterized in detail a mutant line with increased diameter. The phenotype was caused by a poplar homolog of LONELY GUY 1 (LOG1), which encodes an enzyme in cytokinin biosynthesis and significantly increased xylem proliferation. The causative role of LOG1 in the observed phenotype was further reaffirmed by elevated cytokinin concentration in the mutant and recapitulation overexpression experiment wherein multiple independent lines phenocopied the original FOX mutant. Our experiments show that the FOX approach can be efficiently used for gene discovery and molecular interrogation of traits specific to woody perennial growth and development.
- MeSH
- buněčná stěna genetika metabolismus MeSH
- dřevo * genetika metabolismus MeSH
- genová knihovna MeSH
- lignin metabolismus MeSH
- mutační rychlost MeSH
- Populus * genetika metabolismus MeSH
- regulace genové exprese u rostlin genetika MeSH
- rostlinné proteiny genetika metabolismus MeSH
- xylém genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Petroleum hydrocarbons (PHCs) continue to be among the most common pollutants in soil worldwide. Phytoremediation has become a sustainable way of dealing with PHC contamination. We conducted the off-site phytoremediation of PHC-polluted soil from an oil tanker truck accident, where poplars were used for the phytoremediation of the oil-polluted soil in a boreal climate during a seven-year treatment. The succession of bacterial communities over the entire phytoremediation process was monitored using microbial ecological tools relying on high-throughput 16S rRNA gene sequencing. Upon the successful depletion of PHCs from soil, endophytic communities were analyzed in order to assess the complete plant-associated microbiome after the ecological recovery. The rhizosphere-associated soil exhibited different bacterial dynamics than unplanted soil, but both soils experienced succession of bacteria over time, with diversity being negatively correlated with PHC concentration. In the relatively short growing season in North Europe, seasonal variations in environmental conditions were identified that contributed to the dynamics of bacterial communities. Overall, our study proved that phytoremediation using poplar trees can be used to assist in the removal of PHCs from soils in boreal climate conditions and provides new insight into the succession patterns of bacterial communities associated with these plants.
- MeSH
- Bacteria * genetika MeSH
- biodegradace MeSH
- látky znečišťující půdu analýza metabolismus MeSH
- mikrobiální společenstva genetika MeSH
- Populus * MeSH
- půdní mikrobiologie * MeSH
- regenerace a remediace životního prostředí metody MeSH
- rhizosféra MeSH
- RNA ribozomální 16S genetika MeSH
- uhlovodíky analýza metabolismus MeSH
- znečištění ropou * MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Finsko MeSH
Element content and expression of genes of interest on single cell types, such as stomata, provide valuable insights into their specific physiology, improving our understanding of leaf gas exchange regulation. We investigated how far differences in stomatal conductance (gs ) can be ascribed to changes in guard cells functioning in amphistomateous leaves. gs was measured during the day on both leaf sides, on well-watered and drought-stressed trees (two Populus euramericana Moench and two Populus nigra L. genotypes). In parallel, guard cells were dissected for element content and gene expressions analyses. Both were strongly arranged according to genotype, and drought had the lowest impact overall. Normalizing the data by genotype highlighted a structure on the basis of leaf sides and time of day both for element content and gene expression. Guard cells magnesium, phosphorus, and chlorine were the most abundant on the abaxial side in the morning, where gs was at the highest. In contrast, genes encoding H+ -ATPase and aquaporins were usually more abundant in the afternoon, whereas genes encoding Ca2+ -vacuolar antiporters, K+ channels, and ABA-related genes were in general more abundant on the adaxial side. Our work highlights the unique physiology of each leaf side and their analogous rhythmicity through the day.
- MeSH
- genotyp MeSH
- komplementární DNA genetika izolace a purifikace MeSH
- listy rostlin genetika metabolismus MeSH
- mikroanalýza elektronovou sondou MeSH
- období sucha MeSH
- Populus klasifikace genetika metabolismus MeSH
- protonové ATPasy genetika metabolismus MeSH
- průduchy rostlin genetika metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- RNA rostlin genetika izolace a purifikace MeSH
- rostlinné proteiny genetika metabolismus MeSH
- stromy genetika metabolismus MeSH
- transpirace rostlin fyziologie MeSH
- voda fyziologie MeSH
- vývoj rostlin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
MAIN CONCLUSION: Five poplar CHASE-containing histidine kinase receptors bind cytokinins and display kinase activities. Both endogenous isoprenoid and aromatic cytokinins bind to the receptors in live cell assays. Cytokinins are phytohormones that play key roles in various developmental processes in plants. The poplar species Populus × canadensis, cv. Robusta, is the first organism found to contain aromatic cytokinins. Here, we report the functional characterization of five CHASE-containing histidine kinases from P. × canadensis: PcHK2, PcHK3a, PcHK3b, PcHK4a and PcHK4b. A qPCR analysis revealed high transcript levels of all PcHKs other than PcHK4b across multiple poplar organs. The ligand specificity was determined using a live cell Escherichia coli assay and we provide evidence based on UHPLC-MS/MS data that ribosides can be true ligands. PcHK2 exhibited higher sensitivity to iP-type cytokinins than the other receptors, while PcHK3a and PcHK3b bound these cytokinins much more weakly, because they possess two isoleucine residues that clash with the cytokinin base and destabilize its binding. All receptors display kinase activity but their activation ratios in the presence/absence of cytokinin differ significantly. PcHK4a displays over 400-fold higher kinase activity in the presence of cytokinin, suggesting involvement in strong responses to changes in cytokinin levels. trans-Zeatin was both the most abundant cytokinin in poplar and that with the highest variation in abundance, which is consistent with its strong binding to all five HKs and activation of cytokinin signaling via A-type response regulators. The aromatic cytokinins' biological significance remains unclear, their levels vary diurnally, seasonally, and annually. PcHK3 and PcHK4 display the strongest binding at pH 7.5 and 5.5, respectively, in line with their putative membrane localization in the endoplasmic reticulum and plasma membrane.
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.
- MeSH
- alely MeSH
- celogenomová asociační studie MeSH
- druhová specificita MeSH
- fenotyp MeSH
- genotyp MeSH
- imunita rostlin genetika MeSH
- jednonukleotidový polymorfismus genetika MeSH
- kvantitativní znak dědičný MeSH
- podnebí MeSH
- Populus genetika růst a vývoj imunologie fyziologie MeSH
- průduchy rostlin genetika fyziologie MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- rozvržení tělního plánu * MeSH
- vývoj rostlin MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
MAIN CONCLUSION: Isoprenoid and aromatic cytokinins occur in poplar as free compounds and constituents of tRNA, poplar isopentenyltransferases are involved in the production of isoprenoid cytokinins, while biosynthesis of their aromatic counterparts remains unsolved. Cytokinins are phytohormones with a fundamental role in the regulation of plant growth and development. They occur naturally either as isoprenoid or aromatic derivatives, but the latter are quite rare and less studied. Here, the spatial expression of all nine isopentenyl transferase genes of Populus × canadensis cv. Robusta (PcIPTs) as analyzed by RT-qPCR revealed a tissue preference and strong differences in expression levels for the different adenylate and tRNA PcIPTs. Together with their phylogeny, this result suggests a functional diversification for the different PcIPT proteins. Additionally, the majority of PcIPT genes were cloned and expressed in Arabidopsis thaliana under an inducible promoter. The cytokinin levels measured in the Arabidopsis-overexpressing lines as well as their phenotype indicate that the studied adenylate and tRNA PcIPT proteins are functional in vivo and thus will contribute to the cytokinin pool in poplar. We screened the cytokinin content in leaves of 12 Populus species by ultra-high performance-tandem mass spectrometry (UHPLC-MS/MS) and discovered that the capacity to produce not only isoprenoid, but also aromatic cytokinins is widespread amongst the Populus accessions studied. Important for future studies is that the levels of aromatic cytokinins transiently increase after daybreak and are much higher in older plants.
- MeSH
- alkyltransferasy a aryltransferasy genetika metabolismus MeSH
- Arabidopsis genetika metabolismus MeSH
- cytokininy biosyntéza MeSH
- fylogeneze MeSH
- geneticky modifikované rostliny MeSH
- listy rostlin genetika metabolismus MeSH
- Populus genetika metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- rostlinné proteiny genetika metabolismus MeSH
- tandemová hmotnostní spektrometrie MeSH
- Publikační typ
- časopisecké články MeSH
In the context of climate changes, clarifying the causes underlying tree phenotypic plasticity and adaptation is crucial. Studies suggest a role of epigenetic mechanisms in response to external stimuli, raising the question whether such processes can promote acclimation of trees exposed to adverse climate conditions. Recently, we revealed an environmental epigenetic footprint in the shoot apical meristem (SAM) which could partially be transmitted mitotically, for several months, up until the winter-dormant bud in field conditions. Here, we extended our previous analysis to the leaves of the same P. deltoides×P. nigra clones. We aimed at estimating the range of developmentally, genetically, and environmentally induced variations on DNA methylation. We showed that only the first leaves emerging from the SAM displayed variations of DNA methylation under changing water conditions. We also found that these variations are genotype- and pedoclimatic site-dependent. Altogether, our data raised questions and perspectives on the direct acquisition, the maintenance of environmentally induced DNA methylation changes, and their mitotic transmission from the SAM to the first emerging leaves.
Numerous studies demonstrated that endophytic microbes can promote plant growth and increase plant stress resistance. We aimed at isolating poplar endophytes able to increase their hosts' fitness both in nutrient-limited and polluted environments. To achieve this goal, endophytic bacteria and fungi were isolated from roots and leaves of hybrid poplars (Populus nigra × P. maximowiczii clone Max-4) on an unpolluted and a risk element-polluted site in the Czech Republic and subsequently screened by a number of in vitro tests. Bacterial communities at the unpolluted site were dominated by Gammaproteobacteria with Pseudomonas sp. as the prominent member of the class, followed by Bacilli with prevailing Bacillus sp., whereas Alphaproteobacteria, mostly Rhizobium sp., prevailed at the polluted site. The fungal endophytic community was dominated by Ascomycetes and highly distinct on both sites. Dothideomycetes, mostly Cladosporium, prevailed at the non-polluted site while unclassified Sordariomycetous fungi dominated at the polluted site. Species diversity of endophytes was higher at the unpolluted site. Many tested endophytic strains solubilized phosphate and produced siderophores, phytohormones, and antioxidants. Some strains also exhibited ACC-deaminase activity. Selected bacteria showed high tolerance and the ability to accumulate risk elements, making them promising candidates for use in inocula promoting biomass production and phytoremediation. Graphical Abstract ᅟ.
- MeSH
- antioxidancia metabolismus MeSH
- Bacteria klasifikace účinky léků izolace a purifikace metabolismus MeSH
- biodegradace MeSH
- biodiverzita MeSH
- biomasa MeSH
- endofyty klasifikace účinky léků izolace a purifikace metabolismus MeSH
- fosfáty metabolismus MeSH
- fylogeneze MeSH
- houby klasifikace účinky léků izolace a purifikace metabolismus MeSH
- kořeny rostlin mikrobiologie MeSH
- látky znečišťující životní prostředí toxicita MeSH
- listy rostlin mikrobiologie MeSH
- lyasy štěpící vazby C-C metabolismus MeSH
- mikrobiota účinky léků fyziologie MeSH
- Populus mikrobiologie MeSH
- půda chemie MeSH
- půdní mikrobiologie * MeSH
- regulátory růstu rostlin metabolismus MeSH
- siderofory metabolismus MeSH
- techniky in vitro MeSH
- tolerance léku MeSH
- vývoj rostlin * MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
The clones of fast-growing trees (FGTs) were investigated for phytoextraction of soil contaminated with risk elements (REs), especially Cd, Pb, and Zn. As a main experimental factor, the potential effect of biomass harvesting time was assessed. The field experiment with two Salix clones (S1 - (Salix schwerinii × Salix viminalis) × S. viminalis, S2 - S. × smithiana) and two Populus clones (P1 - Populus maximowiczii × Populus nigra, P2 - P. nigra) was established in April 2009. Shoots of all clones were first harvested in February 2012. After two further growing seasons, the first half of the trees was harvested in September 2013 before leaf fall (summer harvest) and the second half in February 2014 (winter harvest). Remediation factors (RFs) for all clones and all REs (except Pb for clone S1) were higher in the summer harvest. The highest annual RFs for Cd and for Zn (1.34 and 0.67%, respectively) were found for clone S2 and were significantly higher than other clones. Although no increased mortality of trees harvested in the summer was detected in the following season, the effect of summer harvesting on the phytoextraction potential of FGTs clones should be investigated in long-term studies.
- MeSH
- biodegradace MeSH
- látky znečišťující půdu analýza MeSH
- Populus * MeSH
- půda MeSH
- roční období MeSH
- Salix * MeSH
- Publikační typ
- časopisecké články MeSH
Spring bud-break phenology is a critical adaptive feature common to temperate perennial woody plants. Understanding the molecular underpinnings of variation in bud-break is important for elucidating adaptive evolution and predicting outcomes relating to climate change. Field and controlled growth chamber tests were used to assess population-wide patterns in bud-break from wild-sourced black cottonwood (Populus trichocarpa) genotypes. We conducted a genome-wide association study (GWAS) with single nucleotide polymorphisms (SNPs) derived from whole genome sequencing to test for loci underlying variation in bud-break. Bud-break had a quadratic relationship with latitude, where southern- and northern-most provenances generally broke bud earlier than those from central parts of the species' range. Reduced winter chilling increased population-wide variation in bud-break, whereas greater chilling decreased variation. GWAS uncovered 16 loci associated with bud-break. Phenotypic changes connected with allelic variation were replicated in an independent set of P. trichocarpa trees. Despite phenotypic similarities, genetic profiles between southern- and northern-most genotypes were dissimilar based on our GWAS-identified SNPs. We propose that the GWAS-identified loci underpin the geographical pattern in P. trichocarpa and that variation in bud-break reflects different selection for winter chilling and heat sum accumulation, both of which can be affected by climate warming.
- MeSH
- alely MeSH
- časové faktory MeSH
- celogenomová asociační studie MeSH
- ekologie a životní prostředí - jevy * MeSH
- fenotyp MeSH
- genetická variace * MeSH
- genetické lokusy MeSH
- genomika * MeSH
- heterozygot MeSH
- jednonukleotidový polymorfismus genetika MeSH
- klimatické změny * MeSH
- květy genetika MeSH
- Populus genetika MeSH
- roční období MeSH
- rostlinné geny MeSH
- vazebná nerovnováha genetika MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Britská Kolumbie MeSH
