title: Aspen Tension Wood Fibers Contain β-(1---> 4)-Galactans and Acidic Arabinogalactans Retained by Cellulose Microfibrils in Gelatinous Walls.
abstract: Contractile cell walls are found in various plant organs and tissues such as tendrils, contractile roots, and tension wood. The tension-generating mechanism is not known but is thought to involve special cell wall architecture. We previously postulated that tension could result from the entrapment of certain matrix polymers within cellulose microfibrils. As reported here, this hypothesis was corroborated by sequential extraction and analysis of cell wall polymers that are retained by cellulose microfibrils in tension wood and normal wood of hybrid aspen (Populus tremula × Populus tremuloides). β-(1→4)-Galactan and type II arabinogalactan were the main large matrix polymers retained by cellulose microfibrils that were specifically found in tension wood. Xyloglucan was detected mostly in oligomeric form in the alkali-labile fraction and was enriched in tension wood. β-(1→4)-Galactan and rhamnogalacturonan I backbone epitopes were localized in the gelatinous cell wall layer. Type II arabinogalactans retained by cellulose microfibrils had a higher content of (methyl)glucuronic acid and galactose in tension wood than in normal wood. Thus, β-(1→4)-galactan and a specialized form of type II arabinogalactan are trapped by cellulose microfibrils specifically in tension wood and, thus, are the main candidate polymers for the generation of tensional stresses by the entrapment mechanism. We also found high β-galactosidase activity accompanying tension wood differentiation and propose a testable hypothesis that such activity might regulate galactan entrapment and, thus, mechanical properties of cell walls in tension wood.
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.) gorshkova@kibb.knc.ru ewa.mellerowicz@slu.se.
authors.forename: Tatyana
authors.identifier: http://orcid.org/0000-0003-0342-8195
authors.initials: T
authors.lastname: Gorshkova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Natalia
authors.initials: N
authors.lastname: Mokshina
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Tatyana
authors.initials: T
authors.lastname: Chernova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Ibragimova
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Vadim
authors.identifier: http://orcid.org/0000-0002-2367-672X
authors.initials: V
authors.lastname: Salnikov
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Polina
authors.initials: P
authors.lastname: Mikshina
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Theodora
authors.initials: T
authors.lastname: Tryfona
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Alicja
authors.initials: A
authors.lastname: Banasiak
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Peter
authors.initials: P
authors.lastname: Immerzeel
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.).
authors.forename: Paul
authors.identifier: http://orcid.org/0000-0001-9270-6286
authors.initials: P
authors.lastname: Dupree
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Centre, Russian Academy of Sciences, 420111 Kazan, Russia (T.G., N.M., T.C., N.I., V.S., P.M.);Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom (T.T., P.D.);Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea Plant Science Centre, 90183 Umea, Sweden (A.B., P.I., E.J.M.); andInstitute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland (A.B.) gorshkova@kibb.knc.ru ewa.mellerowicz@slu.se.
authors.forename: Ewa J
authors.identifier: http://orcid.org/0000-0001-6817-1031
authors.initials: EJ
authors.lastname: Mellerowicz
mesh_terms: D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D002482:Cellulose / Q000737:chemistry / Q000378:metabolism*; D005685:Galactans / Q000737:chemistry / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism; D005780:Gelatin / Q000737:chemistry / Q000378:metabolism; D005936:Glucans / Q000737:chemistry / Q000378:metabolism; D020894:Microfibrils / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D010368:Pectins / Q000737:chemistry / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D032107:Populus / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D014934:Wood / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D014990:Xylans / Q000737:chemistry / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001704:Biopolymers; D005685:Galactans; D005936:Glucans; D011134:Polysaccharides; D014990:Xylans; C042491:rhamnogalacturonan I; C029353:xyloglucan; D010368:Pectins; D005780:Gelatin; D002482:Cellulose; D001616:beta-Galactosidase; C005653:arabinogalactan; D005690:Galactose