Physiological, Anatomical and Metabolic Implications of Salt Tolerance in the Halophyte Salvadora persica under Hydroponic Culture Condition

Abstract

Salt tolerance mechanism of an extreme halophyte Salvadora persica was assessed by analyzing growth, nutrient uptake, anatomical modifications and alterations in levels of some organic metabolites in seedlings imposed to various levels of salinity (0, 250, 500, and 750 mM NaCl) under hydroponic culture condition. After 21 days of salt treatment, plant height, leaf area, and shoot biomass decreased with increase in salinity whereas the leaf succulence increased significantly with increasing salinity in S. persica. The RWC% of leaf increased progressively in salt-treated seedlings as compared to control. Na+ contents of leaf, stem and root increased in dose-dependent manner whereas there was no significant changes in K+ content. There was significant alterations in leaf, stem, and root anatomy by salinity. The thickness of epidermis and spongy parenchyma of leaf increased in salt treated seedlings as compared to control, whereas palisade parenchyma decreased dramatically in extreme salinity (750 mM NaCl). There was a significant reduction in stomatal density and stomatal pore area of leaf with increasing salinity. Anatomical observations of stem showed that the epidermal cells diameter and thickness of cortex decreased by salinity whereas thickness of hypodermal layer, diameter of hypodermal cell, pith area and pith cell diameter increased by high salinity. The root anatomy showed an increase in epidermal thickness by salinity whereas diameters of epidermal cells and xylem vessels decreased. Total soluble sugar content remained unchanged at all levels of salinity whereas reducing sugar content increased by twofold at high salinity (750 mM NaCl). The starch content of leaf decreased progressively in NaCl treated seedlings as compared to control. Total free amino acid content did not change at low salinity (250 mM), whereas it increased significantly at higher salinity (500 and 750 mM NaCl). The proline content increased in NaCl treated seedlings as compared to control. There was no significant changes in polyphenols level of leaf at all levels of salinity. The results from the present study reveal that seedlings imposed with various levels of salinity experience physiological, biochemical and anatomical modifications in order to circumvent under extreme saline environment. The vital mechanisms of salt tolerance in S. persica are higher accumulation of organic metabolites, increase in leaf succulency, efficient Na+ sequestration in the vacuole, K+ retention in the photosynthetic tissue and increase in WUE by reducing stomatal density. Therefore, S. persica is a potential halophytic species to be cultivated in saline lands to eliminate excess salt and make it favorable for agriculture.

Effects of Exogenous Salicylic Acid on Morphological and Biochemical Characteristics of Jatropha Curcas L. Irrigated with Saline Water

“…Also, they suggested that alteration of mineral uptake from SA applications may be one of the mechanisms for alleviation of salt stress, and positively affected K+/Na+ ratio. Similar explanation was reported by Parida et al, (2016). Also, War et al, (2011) concluded that SA plays an important role in induction of plant defensive system against a variety of biotic and abiotic stresses.…”

Effects of seawater irrigation on soil microbial community structure and physiological function

“…In agreement with previous studies, 75-100 % seawater caused a yield reduction in Salicornia persica, Sarcocornia fructicosa and Helianthus tuberosus L. (Zhao et al 2008;Ventura et al 2011); our studies also demonstrated that Salvadora dry matter yield was decreased at 100 % seawater compared to low concentration of seawater (Table 1); however, still this yield was higher than control treatment (0 % seawater) because highest EC of soil in present study was 2.43 dS m -1 which was lower than that of 6.1 dS m -1 where Salvadora exhibited a reduction in growth (Ramoliya et al 2004). Salvadora tolerate the salinity by maintaining osmotic balance and ion homeostasis (Parida et al 2016). Salinityinduced higher accumulation of organic metabolites such as amino acids, reducing sugars and polyphenols was observed (Parida et al 2016).…”

“…Salvadora tolerate the salinity by maintaining osmotic balance and ion homeostasis (Parida et al 2016). Salinityinduced higher accumulation of organic metabolites such as amino acids, reducing sugars and polyphenols was observed (Parida et al 2016).…”

Selection and Breeding of Suitable Crop Genotypes for Drought and Heat Periods in a Changing Climate: Which Morphological and Physiological Properties Should Be Considered?

“…Gas exchange between the atmosphere and the photosynthetically active mesophyll cells is a key aspect and depends on properties of the cuticle, stomatal conductance and mesophyll conductance [106]. Stomatal density and pore area (long-term adaptation, no longer influenced in fully expanded leaves) and the regulation of stomatal opening (reversible short-term adaptation) are highly important for the control of stomatal transpiration and water use efficiency in drought-stressed plants [107][108][109][110]. A reduced stomatal density in halophytes exposed to salt stress (compared to unstressed control plants) was reported by several groups [107][108][109][110] and such adaptations were also considered for selecting/breeding crop varieties with improved abiotic stress tolerance by "learning from halophytes" [109].…”

“…Stomatal density and pore area (long-term adaptation, no longer influenced in fully expanded leaves) and the regulation of stomatal opening (reversible short-term adaptation) are highly important for the control of stomatal transpiration and water use efficiency in drought-stressed plants [107][108][109][110]. A reduced stomatal density in halophytes exposed to salt stress (compared to unstressed control plants) was reported by several groups [107][108][109][110] and such adaptations were also considered for selecting/breeding crop varieties with improved abiotic stress tolerance by "learning from halophytes" [109]. Besides the morphological adaptations in drought-exposed leaves, other important mechanisms are based on changes in the protein pattern (e.g., accumulation of chaperonins or increased activities of enzymes involved in the detoxification of reactive oxygen species or the production of compatible solutes [18,103].…”