EucalyptWood

ABSTRACT: * In response to gravitational stresses, angiosperm trees form tension wood in the upper sides of branches and leaning stems in which cellulose content is higher, microfibrils are typically aligned closely with the fibre axis and the fibres often have a thick inner gelatinous cell wall layer (G-layer). * Gene expression was studied in Eucalyptus nitens branches oriented at 45° using microarrays containing 4 900 xylem cDNAs, and wood fibre characteristics revealed by X-ray diffraction, chemical and histochemical methods. * Xylem fibres in tension wood (upper branch) had a low microfibril angle, contained few fibres with G-layers and had higher cellulose and decreased Klason lignin compared to lower branch wood. Expression of two closely related fasciclin-like arabinogalactan proteins and a B-tubulin was inversely correlated with microfibril angle in upper and lower xylem from branches. * Structural and chemical modifications throughout the secondary cell walls of fibres sufficient to resist tension forces in branches can occur in the absence of G-layer enriched fibres and some important genes involved in responses to gravitational stress in eucalypt xylem are identified. Keywords: tissue comparison Two nine-year-old Eucalyptus nitens trees were used as a source of biological material. RNA was isolated from xylem from the vertical main stem and from the upper and lower quarter of branches oriented at approximately 45° from vertical. For each tree, slides were hybridized with probes synthesized from vertical xylem and one or other of upper or lower branch xylem.

ORGANISM(S): Eucalyptus nitens

SUBMITTER: Andrew Spriggs 

PROVIDER: E-GEOD-8816 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress