title: X-ray micro-computed tomography in willow reveals tissue patterning of reaction wood and delay in programmed cell death.
abstract: BACKGROUND
  Variation in the reaction wood (RW) response has been shown to be a principle component driving differences in lignocellulosic sugar yield from the bioenergy crop willow. The phenotypic cause(s) behind these differences in sugar yield, beyond their common elicitor, however, remain unclear. Here we use X-ray micro-computed tomography (μCT) to investigate RW-associated alterations in secondary xylem tissue patterning in three dimensions (3D).
  
  
  RESULTS
  Major architectural alterations were successfully quantified in 3D and attributed to RW induction. Whilst the frequency of vessels was reduced in tension wood tissue (TW), the total vessel volume was significantly increased. Interestingly, a delay in programmed-cell-death (PCD) associated with TW was also clearly observed and readily quantified by μCT.
  
  
  CONCLUSIONS
  The surprising degree to which the volume of vessels was increased illustrates the substantial xylem tissue remodelling involved in reaction wood formation. The remodelling suggests an important physiological compromise between structural and hydraulic architecture necessary for extensive alteration of biomass and helps to demonstrate the power of improving our perspective of cell and tissue architecture. The precise observation of xylem tissue development and quantification of the extent of delay in PCD provides a valuable and exciting insight into this bioenergy crop trait.
authors.affiliation: Institut de recherche en biologie végétale, Université de Montréal, Montreal, QC, H1X 2B2, Canada. Nicholas.Brereton@UMontreal.ca.
authors.forename: Nicholas James Beresford
authors.initials: NJ
authors.lastname: Brereton
authors.affiliation: Micro-CT Lab, Imaging and Analysis Centre, Natural History Museum, London, SW7 5BD, UK. f.Ahmed@NHM.ac.uk.
authors.forename: Farah
authors.initials: F
authors.lastname: Ahmed
authors.affiliation: Micro-CT Lab, Imaging and Analysis Centre, Natural History Museum, London, SW7 5BD, UK. D.Sykes@NHM.ac.uk.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sykes
authors.affiliation: Department of Chemistry, Imperial College, London, SW7 2AZ, UK. michael.ray@imperial.ac.uk.
authors.forename: Michael Jason
authors.initials: MJ
authors.lastname: Ray
authors.affiliation: Department of AgroEcology, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK. ian.shield@rothamsted.ac.uk.
authors.forename: Ian
authors.initials: I
authors.lastname: Shield
authors.affiliation: Department of AgroEcology, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK. Angela.Karp@rothamsted.ac.uk.
authors.forename: Angela
authors.initials: A
authors.lastname: Karp
authors.affiliation: Centre for Environmental Strategy, University of Surrey, Guildford, Surrey, GU2 7XH, UK. rj.murphy@surrey.ac.uk.
authors.forename: Richard James
authors.initials: RJ
authors.lastname: Murphy
mesh_terms: D016923:Cell Death; D032108:Salix / Q000033:anatomy & histology / Q000196:embryology* / Q000254:growth & development / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D014934:Wood / Q000254:growth & development / Q000502:physiology*; D052584:Xylem / Q000196:embryology / Q000254:growth & development / Q000502:physiology*