Temporal analysis of Arabidopsis genes activated by Eucalyptus grandis NAC transcription factors associated with xylem fibre and vessel development

• Published in: Scientific reports Vol. 8; no. 1; pp. 10983 - 14
• Main Authors: Laubscher, M., Brown, K., Tonfack, L. B., Myburg, A. A., Mizrachi, E., Hussey, S. G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20-07-2018; Nature Publishing Group
• Subjects: 13/109; 14/19; 14/35; 14/63; 38/111; 38/91; 42/44; 631/449; 631/61/191; Apoptosis; Arabidopsis; Cell death; Eucalyptus grandis; Gene expression; Humanities and Social Sciences; Mesophyll; multidisciplinary; Pattern formation; Protoplasts; Reporter gene; Science; Science (multidisciplinary); Transcription factors; Transfection; Xylem
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-29278-w

Secondary cell wall (SCW) deposition in
Arabidopsis
is regulated among others by NAC transcription factors, where SND1 chiefly initiates xylem fibre differentiation while VND6 controls metaxylem vessel SCW development, especially programmed cell death and wall patterning. The translational relevance of
Arabidopsis
SCW regulation theory and the utility of characterized transcription factors as modular synthetic biology tools for improving commercial fibre crops is unclear. We investigated inter-lineage gene activation dynamics for potential fibre and vessel differentiation regulators from the widely grown hardwood
Eucalyptus grandis
(Myrtales).
EgrNAC26
, a
VND6
homolog, and
EgrNAC61
, an
SND1
homolog, were transiently expressed in
Arabidopsis
mesophyll protoplasts in parallel to determine early and late (i.e. 7 and 14 hours post-transfection) gene targets. Surprisingly, across the time series EgrNAC26 activated only a subset of SCW-related transcription factors and biosynthetic genes activated by EgrNAC61, specializing instead in targeting vessel-specific wall pit and programmed cell death markers. Promoters of
EgrNAC26
and
EgrNAC61
both induced reporter gene expression in vessels of young
Arabidopsis
plants, with
EgrNAC61
also conferring xylem- and cork cambium-preferential expression in
Populus
. Our results demonstrate partial conservation, with notable exceptions, of SND1 and VND6 homologs in
Eucalyptus
and a first report of cork cambium expression for EgrNAC61.