title: Non-cell-autonomous postmortem lignification of tracheary elements in Zinnia elegans.
abstract: Postmortem lignification of xylem tracheary elements (TEs) has been debated for decades. Here, we provide evidence in Zinnia elegans TE cell cultures, using pharmacological inhibitors and in intact Z. elegans plants using Fourier transform infrared microspectroscopy, that TE lignification occurs postmortem (i.e., after TE programmed cell death). In situ RT-PCR verified expression of the lignin monomer biosynthetic cinnamoyl CoA reductase and cinnamyl alcohol dehydrogenase in not only the lignifying TEs but also in the unlignified non-TE cells of Z. elegans TE cell cultures and in living, parenchymatic xylem cells that surround TEs in stems. These cells were also shown to have the capacity to synthesize and transport lignin monomers and reactive oxygen species to the cell walls of dead TEs. Differential gene expression analysis in Z. elegans TE cell cultures and concomitant functional analysis in Arabidopsis thaliana resulted in identification of several genes that were expressed in the non-TE cells and that affected lignin chemistry on the basis of pyrolysis-gas chromatography/mass spectrometry analysis. These data suggest that living, parenchymatic xylem cells contribute to TE lignification in a non-cell-autonomous manner, thus enabling the postmortem lignification of TEs.
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 90187 Umea, Sweden. edouard.pesquet@plantphys.umu.se
authors.forename: Edouard
authors.initials: E
authors.lastname: Pesquet
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: András
authors.initials: A
authors.lastname: Gorzsás
authors.forename: Tuula
authors.initials: T
authors.lastname: Puhakainen
authors.forename: Henrik
authors.initials: H
authors.lastname: Serk
authors.forename: Sacha
authors.initials: S
authors.lastname: Escamez
authors.forename: Odile
authors.initials: O
authors.lastname: Barbier
authors.forename: Lorenz
authors.initials: L
authors.lastname: Gerber
authors.forename: Charleen
authors.initials: C
authors.lastname: Courtois-Moreau
authors.forename: Edward
authors.initials: E
authors.lastname: Alatalo
authors.forename: Lars
authors.initials: L
authors.lastname: Paulin
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kangasjärvi
authors.forename: Björn
authors.initials: B
authors.lastname: Sundberg
authors.forename: Deborah
authors.initials: D
authors.lastname: Goffner
authors.forename: Hannele
authors.initials: H
authors.lastname: Tuominen
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D017209:Apoptosis; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D019659:Asteraceae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D001565:Benzoates / Q000494:pharmacology; D002473:Cell Wall / Q000378:metabolism; D002478:Cells, Cultured; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008031:Lignin / Q000378:metabolism*; D009861:Onium Compounds / Q000494:pharmacology; D018547:Plant Stems / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017550:Spectroscopy, Fourier Transform Infrared; D013885:Thiosulfates / Q000494:pharmacology; D052584:Xylem / Q000166:cytology / Q000235:genetics / Q000378:metabolism*
chemical_list: D001565:Benzoates; D009861:Onium Compounds; D013885:Thiosulfates; C095213:silver thiosulfate; C007517:diphenyleneiodonium; D008031:Lignin; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase; D000445:Aldehyde Oxidoreductases; C019904:cinnamoyl CoA reductase; C005455:piperonylic acid; D000111:Acetylcysteine