title: Physiological, phytochemical and structural changes of multi-leaf lettuce caused by salt stress.
abstract: BACKGROUND
  Environmental stress due to salt has been described to enhance lettuce processability, shelf life and consumer acceptability. Moderate salinity causes altered leaf carotenoid, lignin, phenolic and flavonol levels without noticeable changes in the green colour and morphology of lettuce. The aim of this study was to understand the improvements in processability, due to salt stress, related to textural properties and structural characteristics.
  
  
  RESULTS
  Physiological, phytochemical and structural changes were observed that were of significant relevance to salt stress (50, 100 and 150 mmol L(-1) NaCl). Fresh weight per plant, fresh weight per leaf, leaf area, water content, colour saturation, chlorophyll a and b and the area of the intercellular spaces decreased when the concentration of salt was increased. Solute concentration, elasticity, total and individual phenolic acids and the areas occupied by the palisade and spongy parenchyma cells increased when the concentration of salt was increased.
  
  
  CONCLUSIONS
  These data illustrate that salt stress can have a positive impact on certain structural parameters, especially tissue elasticity, that can be closely linked to a higher number of cells, of lower size and high leaf strength, explaining the postharvest longevity of lettuce. However, leaf growth and visual quality could be negatively affected by salt stress.
authors.affiliation: Research Group on Quality, Safety and Bioactivity of Plant Foods, Food Science and Technology Department, CEBAS-CSIC, PO Box 164, E-30100, Espinardo, Murcia, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Garrido
authors.forename: Juan A
authors.initials: JA
authors.lastname: Tudela
authors.forename: Alicia
authors.initials: A
authors.lastname: Marín
authors.forename: Teresa
authors.initials: T
authors.lastname: Mestre
authors.forename: Vicente
authors.initials: V
authors.lastname: Martínez
authors.forename: María I
authors.initials: MI
authors.lastname: Gil
mesh_terms: D002338:Carotenoids / Q000032:analysis; D002473:Cell Wall / Q000502:physiology; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D044948:Flavonols / Q000032:analysis; D005511:Food Handling / Q000379:methods; D018545:Lactuca / Q000033:anatomy & histology* / Q000187:drug effects; D008031:Lignin / Q000032:analysis; D010636:Phenols / Q000032:analysis; D018515:Plant Leaves / Q000033:anatomy & histology / Q000737:chemistry* / Q000502:physiology*; D054712:Salinity; D012965:Sodium Chloride / Q000008:administration & dosage*; D013312:Stress, Physiological; D014867:Water / Q000032:analysis
chemical_list: D044948:Flavonols; D010636:Phenols; D014867:Water; D002734:Chlorophyll; D002338:Carotenoids; D012965:Sodium Chloride; C037184:chlorophyll b; D008031:Lignin; D000077194:Chlorophyll A
keywords: Lactuca sativa; leaf anatomy; phenolics; processability; quality; soilless