Salt stress proteins in plants: An overview

Abstract

Salinity stress is considered the most devastating abiotic stress for crop productivity. Accumulating different types of soluble proteins has evolved as a vital strategy that plays a central regulatory role in the growth and development of plants subjected to salt stress. In the last two decades, efforts have been undertaken to critically examine the genome structure and functions of the transcriptome in plants subjected to salinity stress. Although genomics and transcriptomics studies indicate physiological and biochemical alterations in plants, it do not reflect changes in the amount and type of proteins corresponding to gene expression at the transcriptome level. In addition, proteins are a more reliable determinant of salt tolerance than simple gene expression as they play major roles in shaping physiological traits in salt-tolerant phenotypes. However, little information is available on salt stress-responsive proteins and their possible modes of action in conferring salinity stress tolerance. In addition, a complete proteome profile under normal or stress conditions has not been established yet for any model plant species. Similarly, a complete set of low abundant and key stress regulatory proteins in plants has not been identified. Furthermore, insufficient information on post-translational modifications in salt stress regulatory proteins is available. Therefore, in recent past, studies focused on exploring changes in protein expression under salt stress, which will complement genomic, transcriptomic, and physiological studies in understanding mechanism of salt tolerance in plants. This review focused on recent studies on proteome profiling in plants subjected to salinity stress, and provide synthesis of updated literature about how salinity regulates various salt stress proteins involved in the plant salt tolerance mechanism. This review also highlights the recent reports on regulation of salt stress proteins using transgenic approaches with enhanced salt stress tolerance in crops.

Impact of Salinity on the Energy Transfer between Pigment–Protein Complexes in Photosynthetic Apparatus, Functions of the Oxygen-Evolving Complex and Photochemical Activities of Photosystem II and Photosystem I in Two Paulownia Lines

“…It has been shown that salt concentrations which are harmful to one plant species may not be stressful for another. Previous investigations showed that changes in the proteins of PSII (LHCII, inner antenna of PSII, D1 and OEC) and PSI as well as the degree of the inhibition of photosynthetic performance depend on the salt sensitivity of the plant species [ 18 , 19 , 28 ].…”

“…In addition, data revealed a stronger decrease in the amount of Chl a than Chl b in leaves ( Figure 1 ), which could be a result of the influence on pigment biosynthesis and degradation [ 51 ]. Previous observations have demonstrated that Chl a is more salt-sensitive than Chl b and the primary reason for the decrease in the Chl content after salt stress is the degradation of Chl a [ 28 ]. The other reason for the reduction in the Chl content could be the decreased biosynthesis of the LHCII chlorophylls [ 46 , 72 ], which corresponds with an increase in the Chl a/b ratio and a decrease in the degree of thylakoid stacking [ 53 ].…”

“…Salt-induced structural changes also affect the interactions of chlorophyll and protein molecules, leading to instability in pigment–protein complexes [ 27 , 28 ]. Changes have been observed in the proteins of the light-harvesting complex of PSII (LHCII) [ 29 , 30 , 31 ], oxygen-evolving complex (OEC) [ 32 , 33 ], D1 core protein of PSII [ 9 , 34 , 35 ] and/or PsaB core subunit of PSI [ 36 ].…”

Protective Effects of Sodium Nitroprusside on Photosynthetic Performance of Sorghum bicolor L. under Salt Stress

“…The excess ROS can cause oxidative damage, and thus a strong inhibition of photosynthetic activity [ 5 ]. It has also been shown that salinity modified the contents of several thylakoid membrane polypeptides, including the D1 protein and some polypeptides related to light utilization and oxygen-evolving activity [ 12 , 13 , 14 ]. The observed alterations in the thylakoid membranes and the photosynthetic functions are connected with a decrease in the density of the photosynthetic structures, the relative size of the plastoquinone (PQ) pool, the electron transport to the photosystem I (PSI) end electron acceptors and the probability of their reduction, as well as to an increase in the thermal energy dissipation [ 15 , 16 ].…”

Water and Nutrient Recovery for Cucumber Hydroponic Cultivation in Simultaneous Biological Treatment of Urine and Grey Water

“…Cultivation of cucumber on the NUGE medium resulted in a decrease in the soluble protein content ( Figure 2 D). Plant tissues respond to salt stress by degrading proteins or producing abundant salt stress-related proteins [ 52 ]. Soluble proteins accumulated in plants under salt stress play a key role in osmoregulation but also protect cell membranes, and enzymes from Na + toxicity.…”