Differences in the Structural Chemical Composition of the Primary Xylem of Cactaceae: A Topochemical Perspective
Por:
Maceda, Agustin, Soto-Hernandez, Marcos, Pena-Valdivia, Cecilia B., Trejo, Carlos, Terrazas, Teresa
Publicada:
28 nov 2019
Categoría:
Plant science
Resumen:
The xylem of Cactaceae is a complex system with different types of cells
whose main function is to conduct and store water, mostly during the
development of primary xylem, which has vessel elements and wide-band
tracheids. The anatomy of primary xylem of Cactaceae has been widely
studied, but little is known about its chemical composition. The aim of
this study was to determine the structural chemical composition of the
primary xylem of Cactaceae and to compare it with the anatomy in the
group. Seeds from eight cacti species were used, representing the
Pereskioideae, Opuntioideae, and Cactoideae subfamilies. Seeds were
germinated and grown for 8 months. Subsequently, only the stem of the
seedling was selected, dried, milled, and processed following the TAPPI
T-222 om-02 norm; lignin was quantified using the Klason method and
cellulose with the Kurshner-Hoffer method. Using Fourier transform
infrared spectroscopy, the percentage of syringyl and guaiacyl in lignin
was calculated. Seedlings of each species were fixed, sectioned, and
stained for their anatomical description and fluorescence microscopy
analysis for the topochemistry of the primary xylem. The results showed
that there were significant differences between species (p < 0.05),
except in the hemicelluloses. Through a principal component analysis, it
was found that the amount of extractive-free stem and hot water-soluble
extractives were the variables that separated the species, followed by
cellulose and hemicelluloses since the seedlings developed mainly
parenchyma cells and the conductive tissue showed vessel elements and
wide-band tracheids, both with annular and helical thickenings in
secondary walls. The type of lignin with the highest percentage was
guaiacyl-type, which is accumulated mainly in the vessels, providing
rigidity. Whereas in the wide-band tracheids from metaxylem, syringyl
lignin accumulated in the secondary walls S2 and S3, which permits an
efficient flow of water and gives the plant the ability to endure
difficult conditions during seedling development. Only one species can
be considered to have paedomorphosis since the conductive elements had a
similar chemistry in primary and secondary xylem.
Filiaciones:
Maceda, Agustin:
Colegio Postgrad Ciencias Agr, Programa Bot, Texcoco, Mexico
Soto-Hernandez, Marcos:
Colegio Postgrad Ciencias Agr, Programa Bot, Texcoco, Mexico
Pena-Valdivia, Cecilia B.:
Colegio Postgrad Ciencias Agr, Programa Bot, Texcoco, Mexico
Trejo, Carlos:
Colegio Postgrad Ciencias Agr, Programa Bot, Texcoco, Mexico
Terrazas, Teresa:
Univ Nacl Autonoma Mexico, Inst Biol, Mexico City, DF, Mexico
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