DBPapers
DOI: 10.5593/sgem2017/61/S25.110

NEW INSIGHT INTO FORMATION OF THE SECONDARY WALL OF PLANT FIBRE

D.G. Chukhchin, E.V. Novozhilov, K.S. Bolotova
Tuesday 12 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-12-6 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 61, 845-852 pp, DOI: 10.5593/sgem2017/61/S25.110

ABSTRACT

Fibre formation is one of the key issues in plant biology. The walls of plant fibres consist of several layers with different structural organization, chemical composition and properties. The morphology of the secondary wall largely defines the physical and physicochemical properties of plants. In spite of the progress in knowledge and technical ability, various problems concerning fiber formation remain basically unsolved.

The new data are obtained by visualization of birch Betula pubescens and spruce Picea abies splits after cryomechanical destruction with liquid nitrogen. In the SEM shots one can see the stages of formation of the secondary wall in xylary fibers in detail. It has been established that S1 layer forms at the expense of the carbohydrate storage in protoplast. The formation of the S1 layers spirals is shown. Thickness of individual spiral turn (cross-sectional dimension) is 380-450 nm, angle of spiral’s slope about a fibre axis is 60-70 °. The 100 nm extracellular vesicles (exosomes) are visualized for the first time in internal surface of the fibres. The enzymes excreted by the exosomes participate in the hydrolysis of the S1 layer at the sites of pit formation. Formation of S1 and S2 layers is separated in time. It is discovered that S2 layer of fibre secondary wall develops only after pit formation in S1 layer. Carbohydrates for S2 layer formation move into the fibers through the pits. New stages of secondary wall formation are thereby proposed.

Keywords: ultramicroscopic structure, fibre, pit, secondary wall, exosomes