title: Carry-over of differential salt tolerance in plants grown from dimorphic seeds of Suaeda splendens.
abstract: OBJECTIVE
  Halophytic species often show seed dimorphism, where seed morphs produced by a single individual may differ in germination characteristics. Particular morphs are adapted to different windows of opportunity for germination in the seasonally fluctuating and heterogeneous salt-marsh environment. The possibility that plants derived from the two morphs may also differ physiologically has not been investigated previously.
  
  
  METHODS
  Experiments were designed to investigate the germination characteristics of black and brown seed morphs of Suaeda splendens, an annual, C(4) shrub of non-tidal, saline steppes. The resulting seedlings were transferred to hydroponic culture to investigate their growth and photosynthetic (PSII photochemistry and gas exchange) responses to salinity.
  
  
  RESULTS
  Black seeds germinated at low salinity but were particularly sensitive to increasing salt concentrations, and strongly inhibited by light. Brown seeds were unaffected by light, able to germinate at higher salinities and generally germinated more rapidly. Ungerminated black seeds maintained viability for longer than brown ones, particularly at high salinity. Seedlings derived from both seed morphs grew well at high salinity (400 mol m(-3) NaCl). However, seedlings derived from brown seeds performed poorly at low salinity, as reflected in relative growth rate, numbers of branches produced, F(v)/F(m) and net rate of CO(2) assimilation.
  
  
  CONCLUSIONS
  The seeds most likely to germinate at high salinity in the Mediterranean summer (brown ones) retain a requirement for higher salinity as seedlings that might be of adaptive value. On the other hand, black seeds, which are likely to delay germination until lower salinity prevails, produce seedlings that are less sensitive to salinity. It is not clear why performance at low salinity, later in the life cycle, might have been sacrificed by the brown seeds, to achieve higher fitness at the germination stage under high salinity. Analyses of adaptive syndromes associated with seed dimorphism may need to take account of differences over the entire life cycle, rather than just at the germination stage.
authors.affiliation: Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080-Sevilla, Spain. susana@us.es
authors.forename: Susana
authors.initials: S
authors.lastname: Redondo-Gómez
authors.forename: Enrique
authors.initials: E
authors.lastname: Mateos-Naranjo
authors.forename: Jesús
authors.initials: J
authors.lastname: Cambrollé
authors.forename: Teresa
authors.initials: T
authors.lastname: Luque
authors.forename: M Enrique
authors.initials: ME
authors.lastname: Figueroa
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Davy
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D019663:Chenopodiaceae / Q000378:metabolism / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D018525:Germination / Q000187:drug effects / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000187:drug effects / Q000502:physiology; D054712:Salinity; D012639:Seeds / Q000378:metabolism / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology*; D014867:Water / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water; D002734:Chlorophyll; D012965:Sodium Chloride