title: Root cortical burden influences drought tolerance in maize.
abstract: OBJECTIVE
  Root cortical aerenchyma (RCA) increases water and nutrient acquisition by reducing the metabolic costs of soil exploration. In this study the hypothesis was tested that living cortical area (LCA; transversal root cortical area minus aerenchyma area and intercellular air space) is a better predictor of root respiration, soil exploration and, therefore, drought tolerance than RCA formation or root diameter.
  
  
  METHODS
  RCA, LCA, root respiration, root length and biomass loss in response to drought were evaluated in maize (Zea mays) recombinant inbred lines grown with adequate and suboptimal irrigation in soil mesocosms.
  
  
  RESULTS
  Root respiration was highly correlated with LCA. LCA was a better predictor of root respiration than either RCA or root diameter. RCA reduced respiration of large-diameter roots. Since RCA and LCA varied in different parts of the root system, the effects of RCA and LCA on root length were complex. Greater crown-root LCA was associated with reduced crown-root length relative to total root length. Reduced LCA was associated with improved drought tolerance.
  
  
  CONCLUSIONS
  The results are consistent with the hypothesis that LCA is a driver of root metabolic costs and may therefore have adaptive significance for water acquisition in drying soil.
authors.affiliation: Department of Plant Science, The Pennsylvania State University, University Park, PA 16803, USA.
authors.forename: Raúl E
authors.initials: RE
authors.lastname: Jaramillo
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nord
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Chimungu
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Brown
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Lynch
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology; D055864:Droughts; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology*; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D030821:Plants, Genetically Modified; D012987:Soil; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000254:growth & development / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water; D002244:Carbon
keywords: Root; Zea mays; aerenchyma; cortex; drought; respiration