Responses and tolerance to salt stress in bryophytes

Abstract

During exposure to salt environments, plants could perceive salt signal and transmit the signal to cellular machinery to activate adaptive responses. In bryophytes, salt signal components and transcript factor identified suggest that salt activate adaptive responses to tolerate adverse environments. The ability of bryophytes to tolerate salt is determined by multiple biochemical pathways. Transmembrane transport proteins that mediate ion fluxes play a curial role in ionic and osmotic homeostasis under salt environments. Defense proteins protect cells from denaturation and degradation, as well as from oxidative damage following exposure to salt stress in bryophytes. ABA and salt stress positively affect the expression of common genes that participate in protection plant cells from injure, and ABA may be responsible for the ability to tolerate salt stress in bryophytes. In this paper, we reveal the mechanisms of salt responses and tolerance in bryophytes, and imply conservation between higher plants and bryophytes in response and tolerance to salt stress. IntroductionDue to their sessile nature, plants have to endure adverse environmental conditions such as soil salinity. Excess salts in the soil inhibit plant growth and cause great losses in agricultural productivity worldwide. 1 Therefore, understanding the mechanisms by which plants perceive salt signal and transmit the signal to cellular machinery to active adaptive responses is of fundamental importance to biology. The responses of higher plants to salt stress have been studies intensively at the cellular and molecular levels as well as at the physiological and biochemical levels. 2 However, little is known about the mechanisms underlying salt responses and tolerance in bryophytes.Bryophytes are well known because of their importance in the study of plant systematics and evolution, as well as the tolerance of harsh environments. 3 This review focuses on the responses and tolerance of salt stress in bryophytes. These processes include signal transduction, transcript regulation, ionic and osmotic homeostasis, biosynthesis defense proteins, and the roles of phytohormone in salt stress. Our article will provide the complex mechanisms of salt responses and tolerance in bryophytes. Salt Signal Compoments and Transcript RegulationMolecular and proteomic analyses have shown that several different signal components and transcriptional regulator are involved in salt stress responses. These proteins are phototropin, myelin basic protein kinase, MCamb1 and MCamb2, 14-3-3 like protein and PpDBF1. [4][5][6][7] Phototropin is the blue light receptor that mediates phototropism, chloroplast relocation and stomatal opening in higher plants. 8 In Physcomitrell patens, phototropin and 14-3-3 proteins may work cooperatively to regulate plasma membrane H + -ATPase and maintain ion homeostasis. 4 The 14-3-3 proteins are important eukaryotic regulatory proteins, most of which are involved in cellular signaling pathways. 9 Through regulating the activities of kinases and phosphatase,...

Ecological and physiological peculiarities of bryophytes on a post-technogenic salinized territory

“…They attach to the polar terminal groups of membrane phospholipids and thus stabilize the membrane structure of moss cells under stressful conditions. In addition, high concentrations of sugars in the cell provide vitrification of the cytoplasm and membranes, which gives the cell structures stability and minimizes protein denaturation (Lobachevska et al, 2005;Wang et al, 2008;Bates et al, 2009). Carbohydrates also intercept reactive oxygen species and inhibit the processes of free radical oxidation of biological molecules during the development of oxidative stress induced by salinity.…”

Cold, Salinity, and Drought Stress

“…Recently, it has been shown that overexpression of the trehalose-6-phosphate phosphatase gene OsTPP1 confers salt, osmotic, and ABA tolerance in rice, and results in the activation of stress-responsive genes [42]. The conservation in the mechanisms of salt responses and stress tolerance has been observed between bryophytes and higher plants [43]. Some of the web sites for further study on salinity stress include:…”

Mechanisms of maintenance of cytoplasmic osmotic homeostasis in bryophytes cells under salinity stress

“…Under salinity conditions, high concentrations of Na + and Clions lead to hyperosmotic shock and ion imbalance. One of the main mechanisms regulating the concentration of sodium ions in cytosol is functioning of membrane pumps -H + -ATPases, which create the electrochemical gradient required to remove excess monovalent Na + ions outside the cells or into the vacuole [31]. It is also known that Na + is a major competitor of K + in the metabolic processes of cell.…”

“…In higher vascular plants, these genes were lost during the evolution process. It has been shown that under salinization conditions ion homeostasis in bryophytes cells was significantly dependent on the activity of H + -ATPase (PpSHP1 and PpSHP2) and Na + -ATPase (PpENA1 and PpENA2) [31]. It was experimentally proved that at Physcomitrella patens (Hedw.)…”