INSTITUTO DE FISIOLOGIA VEGETAL
Unidad Ejecutora - UE
Structural and chemical characterization of the xylem of three Blechnum arborescent species
MARÍA L. LUNA; JUAN P. RAMOS GIACOSA; GABRIELA E. GIUDICE; PAULA VIRGINIA FERNÁNDEZ; MARINA CIANCIA; MARIO SAPARRAT
INT ASSOC WOOD ANATOMISTS
Año: 2015 vol. 36 p. 3 - 3
This contribution deals with the study of the xylem in three arborescent species of Blechnum section Lomariocycas from adaptive and evolutive points of view. For this, SEM, TEM, FT-IR spectroscopy and sugar composition analysis were conducted. The overall structure of root and rhizome metaxylem tracheids was similar in the species analyzed, since they showed various facets mainly with scalariform pitting. Different degrees of pit membrane thickness and porosity were observed microscopically depending on tracheid`s stage of maturation. Sometimes, roughly rounded deposits resembling vestures were noted in the outer pit apertures of the tracheids. Under TEM, tracheid-to-parenchyma pit membranes displayed thickenings referred as one-sided tori; some parenchyma cells showed, in addition, features of transfer cells. As the increase in stature creates new constraints in terms of biomechanical support and water transport in plants, it is considered that the characteristics found in Blechnum xylem may be related to an improvement in the flow of water and the prevention of embolism. The chemical analyses performed in roots and rhizomes of B. yungense revealed that a G-type lignin was deposited in the xylem cell walls, with similar lignification levels. Such type of lignin is the most common in ferns, including other arborescent genera. Preliminary results about cell wall polysaccharide composition gave similar results for root and rhizome xylem, suggesting cellulose, xyloglucans and xylans as major components with lesser amounts of mannans and pectins. A higher amount of cellulose could be present in xylematic tissue of rhizome. This information is discussed in relation to its contribution to support of the plant body.