ISSN 1021-4437, Russian Journal of Plant Physiology, 2017, Vol. 64, No. 4, pp. 464–477. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © O.A. Rozentsvet, V.N. Nesterov, E.S. Bogdanova, 2017, published in Fiziologiya Rastenii, 2017, Vol. 64, No. 4, pp. 251–265.
Structural, Physiological, and Biochemical Aspects
of Salinity Tolerance of Halophytes
O. A. Rozentsvet*, V. N. Nesterov, and E. S. Bogdanova
Volga Basin Ecology Institute, Russian Academy of Sciences, Tolyatti, Russia
Received September 2, 2016
Abstract⎯Modern concepts on structural, physiological, and biochemical aspects of salt tolerance of higher
plants were considered. Integral physiological processes, such as growth and photosynthesis of glycophytes
and halophytes in the context of their ecological plasticity, variety of their adaptive strategies developed in the
course of their evolution, and natural selection, were discussed. Analysis of the known anatomical and mor-
phological adaptations of halophytes (succulence, special salt-excreting structures, features associated with
special tissues growth, leaf kranz-anatomy and mesostructure) providing their salt tolerance was conducted.
The most important physiological and biochemical adaptations of such plants to salinity related to uptake,
accumulation and excretion of Na
, peculiarities of membrane composition and the pigment system,
and protection against osmotic and oxidative stresses were described. The association of physiological and
biochemical peculiarities of halophytes with ecological salt tolerance strategy was discussed.
Keywords: halophytes, structure, physiological and biochemical peculiarities, adaptation and resource
Excess content of salts in soil is known to be one of
the main environmental factors limiting plant growth
and productivity [1, 2]. As judged by different esti-
mates, approximately 15–23% of the worldwide land
areas, including the regions used by agriculture, are
covered by salted soils . The increase in salted terri-
tories' area, which is believed to be associated with cli-
mate changes, spreading irrigation, and increase of the
human population, jeopardizes human health, eco-
systems, and national economics [4, 5].
To date, a general concept on the negative impact
of salts on plants has been formed, and this states that
is the main toxic ion for most land plants .
Some plant species are sensitive to Cl
as well as the
most commonly encountered anion of salted soils.
High concentrations of Na
in soil are
known to induce osmotic stress in plants due to the
acute lowering of the water potential of plant root-har-
bored medium, while their excess entering into plant
cells shifts their ionic balance, thereby disturbing
many biochemical and physiological processes .
Osmotic stress is initiated immediately after increasing
the concentration of salts in soil solution leading to the
following event sequence expressed in decline in sto-
mata conductivity, limiting water and CO
decrease in leaf sizes, direct inhibition of cell division
and their elongation, and, finally, retardation of plant
growth [6, 7]. The second phase of negative salt
impact is caused by salt accumulation in plant cells
and their toxic action disrupting enzyme operation
and also by accumulation of a number of intermediate
products inducing plant poisoning . In addition,
increased concentrations of Na
contribute to the formation of reactive oxygen species
(ROS) inducing oxidative stress and subsequent dam-
ages of biomolecules [9, 10].
In dependency on their salinity tolerance, plants
are divided into glycophytes and halophytes. The latter
ecologically physiological group of plants is repre-
sented by the ones with a high potential biological
salinity tolerance. Despite their total designation
reflecting a relation to one ecological factor, halo-
phytes represent an extremely dissimilar group of
plants to which representatives of different taxa, life
forms, ecological groups, and floras belong [11, p. 43].
In the course of evolution, these plants developed the
following special salinity tolerance mechanisms:
(1) selective ions accumulation/exclusion; (2) control
Abbreviations: DGDG—digalactosyldiacyl glycerol; FA—fatty
acid; LHC—light-harvesting complex; MGDG—monogalacto-
syldiacyl glycerol; PC—phosphatidyl choline; PE—phosphatidyl
ethanolamine; PEP—phosphoenol piruvate kinase; PG—phos-
phatidylglycerol; PS—photosystem; RBPC/O—ribuloso bisphos-
phate carboxylase/oxygenase; SHDG—sulfohinovosyldiacyl
glycerol; SOD—superoxide dismutase.