A metabolomic and morphophysiological approach to understanding mangrove
adaptations to saline stress as a consequence of hydrological
Mangrove plants are cyclically exposed to variations in salinity.
However, high salinity for long periods can significantly alter their
metabolism. Here, we studied the effect of contrasting interstitial
salinities (45 ppt vs. 70 ppt) on leaf morpho-physiological traits in
adult Avicennia germinans L. trees in the dry and rainy seasons
in Tampamachoco lagoon, Mexico. In the dry season, there was low
stomatal conductance and low water potential. Plants under 70 ppt of
salinity had significantly lower leaf Ca and Mg concentrations than
those at 45 ppt. The metabolomics results revealed that plants produced
different organic compounds based on the salinity they were exposed to.
The specific leaf area was significantly lower under 70 ppt of salinity
(12.94 ± 0.87 g cm -2) compared to 45 ppt (19.57 ±
1.52 g cm -2) may as a result of the leaf stomatal
conductance responses. Salt glands and trichome density were
significantly higher in the leaves of trees found at the more saline
site. Although mangroves are exposed to freshwater availability, saline,
and tidal variation, prolonged exposure to high salinity results in
morphophysiological and biochemical changes in leaves which facilitates
their survival, even under extremely salt conditions.