| 1. |
- Porth, Ilga, et al.
(författare)
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Evolutionary Quantitative Genomics of Populus trichocarpa
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Forest trees generally show high levels of local adaptation and efforts focusing on understanding adaptation to climate will be crucial for species survival and management. Here, we address fundamental questions regarding the molecular basis of adaptation in undomesticated forest tree populations to past climatic environments by employing an integrative quantitative genetics and landscape genomics approach. Using this comprehensive approach, we studied the molecular basis of climate adaptation in 433 Populus trichocarpa (black cottonwood) genotypes originating across western North America. Variation in 74 field-assessed traits (growth, ecophysiology, phenology, leaf stomata, wood, and disease resistance) was investigated for signatures of selection (comparing Q(ST)-F-ST) using clustering of individuals by climate of origin (temperature and precipitation). 29,354 SNPs were investigated employing three different outlier detection methods and marker-inferred relatedness was estimated to obtain the narrow-sense estimate of population differentiation in wild populations. In addition, we compared our results with previously assessed selection of candidate SNPs using the 25 topographical units (drainages) across the P. trichocarpa sampling range as population groupings. Narrow-sense QST for 53% of distinct field traits was significantly divergent from expectations of neutrality (indicating adaptive trait variation); 2,855 SNPs showed signals of diversifying selection and of these, 118 SNPs (within 81 genes) were associated with adaptive traits (based on significant QST). Many SNPs were putatively pleiotropic for functionally uncorrelated adaptive traits, such as autumn phenology, height, and disease resistance. Evolutionary quantitative genomics in P. trichocarpa provides an enhanced understanding regarding the molecular basis of climate-driven selection in forest trees and we highlight that important loci underlying adaptive trait variation also show relationship to climate of origin. We consider our approach the most comprehensive, as it uncovers the molecular mechanisms of adaptation using multiple methods and tests. We also provide a detailed outline of the required analyses for studying adaptation to the environment in a population genomics context to better understand the species' potential adaptive capacity to future climatic scenarios.
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| 2. |
- Bhalla, Aditya, et al.
(författare)
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Engineered Lignin in Poplar Biomass Facilitates Cu-Catalyzed Alkaline-Oxidative
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:3, s. 2932-2941
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Tidskriftsartikel (refereegranskat)abstract
- Both untransformed poplar and genetically modified “zip-lignin” poplar, in which additional ester bonds were introduced into the lignin backbone, were subjected to mild alkaline and copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment. Our hypothesis was that the lignin in zip-lignin poplar would be removed more easily than lignin in untransformed poplar during this alkaline pretreatment, resulting in higher sugar yields following enzymatic hydrolysis. We observed improved glucose and xylose hydrolysis yields for zip-lignin poplar compared to untransformed poplar following both alkaline-only pretreatment (56% glucose yield for untransformed poplar compared to 67% for zip-lignin poplar) and Cu-AHP pretreatment (77% glucose yield for untransformed poplar compared to 85% for zip-lignin poplar). Compositional analysis, glycome profiling, and microscopy all supported the notion that the ester linkages increase delignification and improve sugar yields. Essentially no differences were noted in the molecular weight distributions of solubilized lignins between the zip-lignin poplar and the control line. Significantly, when zip-lignin poplar was utilized as the feedstock, hydrogen peroxide, catalyst, and enzyme loadings could all be substantially reduced while maintaining high sugar yields.
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| 3. |
- Quentin, Audrey G, et al.
(författare)
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Non-structural carbohydrates in woody plants compared among laboratories.
- 2015
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Ingår i: Tree physiology. - : Oxford University Press (OUP). - 1758-4469 .- 0829-318X. ; 35:11, s. 1146-1165
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Tidskriftsartikel (refereegranskat)abstract
- Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g(-1) for soluble sugars, 6-533 (mean = 94) mg g(-1) for starch and 53-649 (mean = 153) mg g(-1) for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R(2) = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g(-1) for total NSC, compared with the range of laboratory estimates of 596 mg g(-1). Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory may be comparable within and between laboratories, especially for starch. To obtain comparable NSC estimates, we suggest that users can either adopt the reference method given in this publication, or report estimates for a portion of samples using the reference method, and report estimates for a standard reference material. Researchers interested in NSC estimates should work to identify and adopt standard methods.
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| 4. |
- Bünder, Anne, et al.
(författare)
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CELLULOSE SYNTHASE INTERACTING 1 is required for wood mechanics and leaf morphology in aspen
- 2020
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Ingår i: The Plant Journal. - : John Wiley & Sons. - 0960-7412 .- 1365-313X. ; 103:5, s. 1858-1868
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose microfibrils synthesized by CELLULOSE SYNTHASE COMPLEXES (CSCs) are the main load‐bearing polymers in wood. CELLULOSE SYNTHASE INTERACTING1 (CSI1) connects CSCs with cortical microtubules, which align with cellulose microfibrils. Mechanical properties of wood are dependent on cellulose microfibril alignment and structure in the cell walls, but the molecular mechanism(s) defining these features is unknown. Herein, we investigated the role of CSI1 in hybrid aspen (Populus tremula × Populus tremuloides ) by characterizing transgenic lines with significantly reduced CSI1 transcript abundance. Reduction in leaves (50–80%) caused leaf twisting and misshaped pavement cells, while reduction (70–90%) in developing xylem led to impaired mechanical wood properties evident as a decrease in the elastic modulus and rupture. X‐ray diffraction measurements indicate that microfibril angle was not impacted by the altered CSI1 abundance in developing wood fibres. Instead, the augmented wood phenotype of the transgenic trees was associated with a reduced cellulose degree of polymerization. These findings establish a function for CSI1 in wood mechanics and in defining leaf cell shape. Furthermore, the results imply that the microfibril angle in wood is defined by CSI1 independent mechanism(s).
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| 5. |
- Kumar, Manoj, et al.
(författare)
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An update on the nomenclature for the cellulose synthase genes in Populus
- 2009
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 14:5, s. 248-254
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Forskningsöversikt (refereegranskat)abstract
- Cellulose synthase (CesA) is a central catalyst in the generation of the plant cell wall biomass and is, therefore, the focus of intense research. Characterization of individual CesA genes from Populus species has led to the publication of several different naming conventions for CesA gene family members in this model tree. To help reduce the resulting confusion, we propose here a new phylogeny-based CesA nomenclature that aligns the Populus CesA gene family with the established Arabidopsis thaliana CesA family structure.
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| 6. |
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| 7. |
- Schneider, Rene, et al.
(författare)
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Two Complementary Mechanisms Underpin Cell Wall Patterning during Xylem Vessel Development
- 2017
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 29:10, s. 2433-2449
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of the plant vasculature was essential for the emergence of terrestrial life. Xylem vessels are solute-transporting elements in the vasculature that possess secondary wall thickenings deposited in intricate patterns. Evenly dispersed microtubule (MT) bands support the formation of these wall thickenings, but how the MTs direct cell wall synthesis during this process remains largely unknown. Cellulose is the major secondary wall constituent and is synthesized by plasma membrane-localized cellulose synthases (CesAs) whose catalytic activity propels them through the membrane. We show that the protein CELLULOSE SYNTHASE INTERACTING1 (CSI1)/POM2 is necessary to align the secondary wall CesAs and MTs during the initial phase of xylem vessel development in Arabidopsis thaliana and rice (Oryza sativa). Surprisingly, these MT-driven patterns successively become imprinted and sufficient to sustain the continued progression of wall thickening in the absence of MTs and CSI1/POM2 function. Hence, two complementary principles underpin wall patterning during xylem vessel development.
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| 8. |
- Stålbrand, Henrik, et al.
(författare)
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Analysis of Molecular Size Distributions of Cellulose Molecules during Hydrolysis of Cellulose by Recombinant Cellulomonas fimi -1,4-Glucanases
- 1998
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 64:7, s. 2374-2379
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Tidskriftsartikel (refereegranskat)abstract
- Four -1,4-glucanases (cellulases) of the cellulolytic bacterium Cellulomonas fimi were purified from Escherichia coli cells transformed with recombinant plasmids. Previous analyses using soluble substrates had suggested that CenA and CenC were endoglucanases while CbhA and CbhB resembled the exo-acting cellobiohydrolases produced by cellulolytic fungi. Analysis of molecular size distributions during cellulose hydrolysis by the individual enzymes confirmed these preliminary findings and provided further evidence that endoglucanase CenC has a more processive hydrolytic activity than CenA. The significant differences between the size distributions obtained during hydrolysis of bacterial microcrystalline cellulose and acid-swollen cellulose can be explained in terms of the accessibility of -1,4-glucan chains to enzyme attack. Endoglucanases and cellobiohydrolases were much more easily distinguished when the acid-swollen substrate was used.
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