2 research outputs found
Salt excretion in Suaeda fruticosa
Suaeda fruticosa is a perennial “includer” halophyte devoid of glands or trichomes with a strong ability
of accumulating and sequestrating Na+ and Cl
–. We were interested in determining whether leaf cuticle
salt excretion could be involved as a further mechanism in salt response of this species after long-term
treatment with high salinity levels. Seedlings had been treated for three months with seawater (SW)
diluted with tap water (0, 25, 50 and 75% SW). Leaf scanning electron microscopy revealed a convex
adaxial side sculpture and a higher accumulation of saline crystals at the lamina margin, with a large
variability on repartition and size between treatments. No salt gland or salt bladder was found. Threedimensional
wax decorations were the only structures found on leaf surface. Washing the leaf surface with
water indicated that sodium and chloride predominated in excreted salts, and that potassium was poorly
represented. Optimal growth of whole plant was recorded at 25% SW, correlating with maximum Na+ and
Cl
– absolute secretion rate. The leaves of plants treated with SW retained more water than those of plants
treated with tap water due to lower solute potential, especially at 25% SW. Analysis of compatible solute,
such as proline, total soluble carbohydrates and glycinebetaine disclosed strong relationship between
glycinebetaine and osmotic potential (r = 0.92) suggesting that tissue hydration was partly maintained by
glycinebetaine accumulation. Thus in S. fruticosa, increased solute accumulation associated with water
retention, and steady intracellular ion homeostasis confirms the “includer” strategy of salt tolerance previously
demonstrated. However, salt excretion at leaf surface also participated in conferring to this species
a capacity in high salinity tolerance