title: Red:far-red light conditions affect the emission of volatile organic compounds from barley (Hordeum vulgare), leading to altered biomass allocation in neighbouring plants.
abstract: OBJECTIVE
  Volatile organic compounds (VOCs) play various roles in plant-plant interactions, and constitutively produced VOCs might act as a cue to sense neighbouring plants. Previous studies have shown that VOCs emitted from the barley (Hordeum vulgare) cultivar 'Alva' cause changes in biomass allocation in plants of the cultivar 'Kara'. Other studies have shown that shading and the low red:far-red (R:FR) conditions that prevail at high plant densities can reduce the quantity and alter the composition of the VOCs emitted by Arabidopsis thaliana, but whether this affects plant-plant signalling remains unknown. This study therefore examines the effects of far-red light enrichment on VOC emissions and plant-plant signalling between 'Alva' and 'Kara'.
  
  
  METHODS
  The proximity of neighbouring plants was mimicked by supplemental far-red light treatment of VOC emitter plants of barley grown in growth chambers. Volatiles emitted by 'Alva' under control and far-red light-enriched conditions were analysed using gas chromatography-mass spectrometry (GC-MS). 'Kara' plants were exposed to the VOC blend emitted by the 'Alva' plants that were subjected to either of the light treatments. Dry matter partitioning, leaf area, stem and total root length were determined for 'Kara' plants exposed to 'Alva' VOCs, and also for 'Alva' plants exposed to either control or far-red-enriched light treatments.
  
  
  RESULTS
  Total VOC emissions by 'Alva' were reduced under low R:FR conditions compared with control light conditions, although individual volatile compounds were found to be either suppressed, induced or not affected by R:FR. The altered composition of the VOC blend emitted by 'Alva' plants exposed to low R:FR was found to affect carbon allocation in receiver plants of 'Kara'.
  
  
  CONCLUSIONS
  The results indicate that changes in R:FR light conditions influence the emissions of VOCs in barley, and that these altered emissions affect VOC-mediated plant-plant interactions.
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden.
authors: Wouter
authors: W
authors: Kegge
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden.
authors: Velemir
authors: V
authors: Ninkovic
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden.
authors: Robert
authors: R
authors: Glinwood
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden.
authors: Rob A M
authors: RA
authors: Welschen
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden.
authors: Laurentius A C J
authors: LA
authors: Voesenek
authors: Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands and Swedish University of Agricultural Sciences, Department of Crop Production Ecology, PO Box 7043, S-750 07 Uppsala, Sweden r.pierik@uu.nl.
authors: Ronald
authors: R
authors: Pierik
mesh_terms: D018533:Biomass; D005030:Ethylenes / Q000378:metabolism; D001467:Hordeum / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D008027:Light; D010944:Plants / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D005030:Ethylenes; D055549:Volatile Organic Compounds; C036216:ethylene
keywords: Barley; Hordeum vulgare; VOCs; biomass allocation; ethylene; light quality; phytochrome; plant density; plant–plant signalling; red:far-red ratio; shade avoidance; volatile organic compounds