Abstract

Comparative studies were conducted on composition of lignin produced both in vivo and in vitro by cinnamyl alcohol dehydrogenase (CAD)-deficient mutant loblolly pine (Pinus taeda L.). In vivo studies were performed using differentiating xylem obtained from two genotypes of heterozygous (CAD/cad) and two genotypes of homozygous (cad/cad) CAD-deficient mutant trees. In vitro studies were performed using a culture system in which cells, generated from the same genotypes, were induced to produce lignin in culture. Steady state RNA levels and enzyme activity of CAD were dramatically reduced in both xylem and cultured cells obtained from homozygous mutant trees, compared to their heterozygous counterparts. Light microscopic studies showed pronounced differences during the lignin formation between homozygous and heterozygous cells. Phenolic compounds in the heterozygous (CAD/cad) cells were deposited around the cell wall, accumulated preferentially in vacuoles of the homozygous (cad/cad) cells. Differences in lignin composition as revealed by thioacidolysis were also observed. Lignin of both xylem tissue and cultured cells obtained from CAD-deficient homozygotes showed lower levels of coniferyl alcohols and significant enrichments in dihydroconiferyl alcohol (DHCA) and coniferyl. aldehyde, compared to their heterozygous counterparts. The striking similarities in lignin composition observed both in vivo and in vitro, open new possibilities for the use of culture systems aimed at revealing the mechanisms controlling lignin biosynthesis, and the formation of DHCA subunits. (C) 2003 Published by Editions scientifiques et medicales Elsevier SAS.

Keywords

cinnamyl alcohol dehydrogenase; cultured cells; dihydroconiferyl alcohol; lignin; Pinus taeda; xylem

Published in

Plant Physiology and Biochemistry
2003, Volume: 41, number: 5, pages: 439-445

UKÄ Subject classification

Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.1016/S0981-9428(03)00051-2

Permanent link to this page (URI)

https://res.slu.se/id/publ/88484