Structure and spacing of cellulose microfibrils in woody cell walls of dicots

The structure of cellulose microfibrils in situ in wood from the dicotyledonous (hardwood) species cherry and birch, and the vascular tissue from sunflower stems, was examined by wide-angle X-ray and neutron scattering (WAXS and WANS) and small-angle neutron scattering (SANS). Deuteration of accessible cellulose chains followed by WANS showed that these chains were packed at similar spacings to crystalline cellulose, consistent with their inclusion in the microfibril dimensions and with a location at the surface of the microfibrils. Using the Scherrer equation and correcting for considerable lateral disorder, the microfibril dimensions of cherry, birch and sunflower microfibrils perpendicular to the [200] crystal plane were estimated as 3.0, 3.4 and 3.3 nm respectively. The lateral dimensions in other directions were more difficult to correct for disorder but appeared to be 3 nm or less. However for cherry and sunflower, the microfibril spacing estimated by SANS was about 4 nm and was insensitive to the presence of moisture. If the microfibril width was 3 nm as estimated by WAXS, the SANS spacing suggests that a non-cellulosic polymer segment might in places separate the aggregated cellulose microfibrils

Evaluating the potential of Eucalyptus bosistoana essential oil

Eucalypt essential oils are manufactured at commercial scale in many countries, but not in New Zealand. Recent research at the University of Canterbury School of Forestry investigated the potential for essential oil to be produced as an economic by-product of Eucalyptus bosistoana plantations. This eucalypt is a Class 1 durable species, selected by the NZ Dryland Forests Initiative for genetic improvement. The conclusion reached was that producing commercial essential oil as a by-product of timber plantations may well have economic potential

Diffraction evidence for the structure of cellulose microfibrils in bamboo, a model for grass and cereal celluloses

Background: Cellulose from grasses and cereals makes up much of the potential raw material for biofuel production. It is not clear if cellulose microfibrils from grasses and cereals differ in structure from those of other plants. The structures of the highly oriented cellulose microfibrils in the cell walls of the internodes of the bamboo Pseudosasa amabilis are reported. Strong orientation facilitated the use of a range of scattering techniques. Results: Small-angle neutron scattering provided evidence of extensive aggregation by hydrogen bonding through the hydrophilic edges of the sheets of chains. The microfibrils had a mean centre-to-centre distance of 3.0 nm in the dry state, expanding on hydration. The expansion on hydration suggests that this distance between centres was through the hydrophilic faces of adjacent microfibrils. However in the other direction, perpendicular to the sheets of chains, the mean, disorder-corrected Scherrer dimension from wide-angle X-ray scattering was 3.8 nm. It is possible that this dimension is increased by twinning (crystallographic coalescence) of thinner microfibrils over part of their length, through the hydrophobic faces. The wide-angle scattering data also showed that the microfibrils had a relatively large intersheet d-spacing and small monoclinic angle, features normally considered characteristic of primary-wall cellulose. Conclusions: Bamboo microfibrils have features found in both primary-wall and secondary-wall cellulose, but are crystallographically coalescent to a greater extent than is common in celluloses from other plants. The extensive aggregation and local coalescence of the microfibrils are likely to have parallels in other grass and cereal species and to influence the accessibility of cellulose to degradative enzymes during conversion to liquid biofuel

Assessment of E. globoideawood properties at Atkinson

EXECUTIVE SUMMARY This report refers to the SWP work plan WP060 ‘Wood quality assessment of E. globoidea’. While growth characteristics of E. globoidea compare favourably to other eucalypt species in the NZDFI programme, its wood properties in particular natural durability (class 2), ease of drying and to some degree stiffness are good rather than exceptional. Therefore, wood properties should be considered in a tree breeding programme if ground durable solid wood products are envisioned as the future market. 144 families of E. globoidea were assessed at age 8 years old for heartwood quantity, extractive content (i.e. natural durability), drying defects (i.e. collapse) and stiffness (i.e. acoustic velocity). All traits were heritable and having a degree of variation enabling improvements through a breeding programme. The high heritability (h 2 = 1.16) and large coefficient of genetic variation (CGV = 52%) of heartwood extractive content encourages selection for heartwood quality, as E. globoidea is in contrast to the other NZDFI species rated not class 1 but class 2 ground durable. An unfavourable genetic correlation (-0.44; CI95 -0.62, -0.25) was found between heartwood quantity and extractive content, indicating the need for compromise between growth and natural durability. A favourable less strong genetic correlation (-0.27; CI95 -0.51, -0.02) was found between heartwood collapse and extractive content, indicating improvement in both if one is selected for. The other key traits were not correlated and therefore need to be selected for independently. That data has been made available to the NZDFI partners to allow them to select superior genetics for commercial plant production. Only 1 of 3 sites planted at the same time with the same genetics was assessed and environmental effects remain to be quantified

Cell organelles and fluorescence of parenchyma cells in Eucalyptus bosistoana sapwood and heartwood investigated by microscopy

Abstract Background Eucalyptus bosistoana is currently investigated in New Zealand for its potential to produce naturally durable timber in short-rotation plantations. Little is known of heartwood formation in young trees. The objective of this study was to identify conventional and confocal microscopy methods which allow the observation of cell organelles and the chemical composition in the E. bosistoana parenchyma cells before and after heartwood formation. Results Nuclei, microtubules and peroxisomes in parenchyma cells of 2-year-old E. bosistoana stems were visualised by confocal microscopy combined with optimised immunolabelling protocols. Sequential staining of the tissue with toluidine blue and iodine/potassium iodide identified different cell organelles in parenchyma cells of sapwood. Iodine/potassium iodide stained starch (amyloplasts), while amido black stained proteins in sapwood. Fluorescence emission spectra confirmed the presence of chloroplasts in parenchyma of 2-year-old E. bosistoana. Fluorescence emission spectral (lambda) scans showed differences between parenchyma and fibre cells as well as sapwood and heartwood. Conclusions Physiological changes between sapwood and heartwood were visualised in parenchyma cells. Labelling of cell organelles was challenging due to unspecific binding and high background signals. Understanding heartwood formation is critical for the success of a plantation forest industry aiming to produce ground-durable timber, as heartwood formation is variable

Cellulose Iβ investigated by IR-spectroscopy at low temperatures

Highly crystalline oriented Halocynthia roretzi cellulose Iβ films were investigated by IR-spectroscopy between −180 and +10 °C. Changes in the IR-spectra induced by temperature were compared to published changes induced by mechanical stretching. This made it possible to conclude that frequency shifts in the O–H stretching region of the IR-spectra due to temperature were not predominantly an indirect effect of thermal expansion leading to greater O–O distances, but were due directly to the effect of temperature on the O–H···O hydrogen bonds. Temperature induced frequency shifts of C–H stretching bands were consistent with the presence of weak inter-sheet C–H···O bonds. Furthermore, no phase transition in cellulose Iβ was found between −180 and +10 °C

Nanostructural deformation of high-stiffness spruce wood under tension

Conifer wood is an exceptionally stiff and strong material when its cellulose microfibrils are well aligned. However, it is not well understood how the polymer components cellulose, hemicelluloses and lignin co-operate to resist tensile stress in wood. From X-ray scattering, neutron scattering and spectroscopic data, collected under tension and processed by novel methods, the ordered, disordered and hemicellulose-coated cellulose components comprising each microfibril were shown to stretch together and demonstrated concerted, viscous stress relaxation facilitated by water. Different cellulose microfibrils did not all stretch to the same degree. Attempts were made to distinguish between microfibrils showing large and small elongation but these domains were shown to be similar with respect to orientation, crystalline disorder, hydration and the presence of bound xylan. These observations are consistent with a major stress transfer process between microfibrils being shear at interfaces in direct, hydrogen-bonded contact, as demonstrated by small-angle neutron scattering. If stress were transmitted between microfibrils by bridging hemicelluloses these might have been expected to show divergent stretching and relaxation behaviour, which was not observed. However lignin and hemicellulosic glucomannans may contribute to stress transfer on a larger length scale between microfibril bundles (macrofibrils)

Diversidade e estrutura genética espacial em duas populações de Myracrodruon urundeuva Fr. All. sob diferentes condições antrópicas Diversity and spatial genetic structure in two populations of Myracrodruon urundeuva Fr. All. under different antropic conditions

O objetivo deste trabalho foi estudar, por locos isoenzimáticos, a diversidade e a estrutura genética espacial de genótipos de Myracrodruon urundeuva em duas populações naturais, uma no Sudoeste (Selvíria-SEL) e outra no Sudeste (Paulo de Faria-PFA) do Brasil. Para isso, foram avaliados cinco sistemas isoenzimáticos, 25 e 30 indivíduos adultos das populações SEL e PFA, respectivamente. A estimativa da divergência genética entre populações foi baixa (=0,043). As heterozigosidades observada e esperada foram altas nas populações (0,317 e 0,511, respectivamente), e o excesso significativo de heterozigotos foi detectado na população PFA (= -0,252). A análise da distribuição genética espacial dos genótipos a partir do índice I de Moran revelou estruturação significativa até 5.224 m na população mais explorada (SEL, =0,09) e tendência à distribuição aleatória na população menos explorada (PFA, = -0,02). A provável causa da estruturação na população SEL foi a dispersão de sementes próxima às árvores-matriz, associada ao processo de recolonização a partir de sementes oriundas de poucos genótipos remanescentes. As implicações dos resultados são discutidas do ponto de vista da conservação e do melhoramento genético.<br>The diversity and spatial genetic distribution of Myracrodruon urundeuva genotypes were studied in two Brazilian populations in the Southwest (Selvíria-SEL) and Southeast Brazilian regions (Paulo de Faria-PFA). Twenty-five and thirty adult individuals were evaluated for five allozyme systems in SEL and PFA populations, respectively. Estimates of the genetic divergence between populations were low (=0.043). Observed and expected heterozygosities were high in both populations (0.317 to 0.511, respectively). Significant and excessive number of heterozygotes was detected in PFA population (=-0.252). The spatial distribution analysis through Moran's index I revealed a significant structuring up to 5,224 m in the more exploited population (SEL, =0.09) and a trend to randomness in the less exploited area (PFA, = -0,02). Seed dispersion near mother trees and the recolonization process through seeds from few genotypes are probable causes of the structuring in the SEL population. The implications of the results are discussed from the conservation and breeding point of views