Journal Article

Carry-over of Differential Salt Tolerance in Plants Grown from Dimorphic Seeds of <i>Suaeda splendens</i>

Susana Redondo-Gómez, Enrique Mateos-Naranjo, Jesús Cambrollé, Teresa Luque, M. Enrique Figueroa and Anthony J. Davy

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 102, issue 1, pages 103-112
Published in print July 2008 | ISSN: 0305-7364
Published online May 2008 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcn069
Carry-over of Differential Salt Tolerance in Plants Grown from Dimorphic Seeds of Suaeda splendens

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

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, C4 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.

Key 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, Fv/Fm and net rate of CO2 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.

Keywords: Chlorophyll fluorescence; germination; growth rate; halophyte; photosynthesis; photosystem II; salt tolerance; seed dimorphism; seed viability; Suaeda splendens

Journal Article.  6641 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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