title: Salt stress induces the formation of a novel type of 'pressure wood' in two Populus species.
abstract: • Salinity causes osmotic stress and limits biomass production of plants. The goal of this study was to investigate mechanisms underlying hydraulic adaptation to salinity. • Anatomical, ecophysiological and transcriptional responses to salinity were investigated in the xylem of a salt-sensitive (Populus × canescens) and a salt-tolerant species (Populus euphratica). • Moderate salt stress, which suppressed but did not abolish photosynthesis and radial growth in P. × canescens, resulted in hydraulic adaptation by increased vessel frequencies and decreased vessel lumina. Transcript abundances of a suite of genes (FLA, COB-like, BAM, XET, etc.) previously shown to be activated during tension wood formation, were collectively suppressed in developing xylem, whereas those for stress and defense-related genes increased. A subset of cell wall-related genes was also suppressed in salt-exposed P. euphratica, although this species largely excluded sodium and showed no anatomical alterations. Salt exposure influenced cell wall composition involving increases in the lignin : carbohydrate ratio in both species. • In conclusion, hydraulic stress adaptation involves cell wall modifications reciprocal to tension wood formation that result in the formation of a novel type of reaction wood in upright stems named 'pressure wood'. Our data suggest that transcriptional co-regulation of a core set of genes determines reaction wood composition.
authors: Forstbotanik und Baumphysiologie, Büsgen-Institut, Georg-August-Universität Göttingen, Göttingen, Germany.
authors: Dennis
authors: D
authors: Janz
authors: Zentrum für Holzwirtschaft, Universität Hamburg, Hamburg, Germany.
authors: Silke
authors: S
authors: Lautner
authors: Institut für Forstbotanik und Baumphysiologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.
authors: Henning
authors: H
authors: Wildhagen
authors: Institute of Biochemical Plant Pathology, Research Unit Environmental Simulation, Helmholtz Zentrum München, Munchen, Germany.
authors: Katja
authors: K
authors: Behnke
authors: Institute of Biochemical Plant Pathology, Research Unit Environmental Simulation, Helmholtz Zentrum München, Munchen, Germany.
authors: Jörg-Peter
authors: JP
authors: Schnitzler
authors: Institut für Forstbotanik und Baumphysiologie, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.|King Saud University, Riyadh, Saudi Arabia.
authors: Heinz
authors: H
authors: Rennenberg
authors: Zentrum für Holzwirtschaft, Universität Hamburg, Hamburg, Germany.
authors: Jörg
authors: J
authors: Fromm
authors: Forstbotanik und Baumphysiologie, Büsgen-Institut, Georg-August-Universität Göttingen, Göttingen, Germany.
authors: Andrea
authors: A
authors: Polle
mesh_terms: D015152:Blotting, Northern; D003433:Crosses, Genetic; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D009088:Mucoproteins / Q000235:genetics / Q000378:metabolism; D009995:Osmosis / Q000187:drug effects; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D011312:Pressure; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018085:Regulon / Q000235:genetics; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D014934:Wood / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D052584:Xylem / Q000033:anatomy & histology / Q000187:drug effects / Q000235:genetics
chemical_list: D009088:Mucoproteins; D010940:Plant Proteins; D012333:RNA, Messenger; C006619:arabinogalactan proteins; D012965:Sodium Chloride; D012964:Sodium