Molecular insights into the role of plant transporters in salt stress response

Abstract

Salt stress disturbs the cellular osmotic and ionic balance, which then creates a negative impact on plant growth and development. The Na+ and Cl− ions can enter into plant cells through various membrane transporters, including specific and non‐specific Na+, K+, and Ca2+ transporters. Therefore, it is important to understand Na+ and K+ transport mechanisms in plants along with the isolation of genes, their characterization, the structural features, and their post‐translation regulation under salt stress. This review summarizes the molecular insights of plant ion transporters, including non‐selective cation transporters, cyclic nucleotide‐gated cation transporters, glutamate‐like receptors, membrane intrinsic proteins, cation proton antiporters, and sodium proton antiporter families. Further, we discussed the K+ transporter families such as high‐affinity K+ transporters, HAK/KUP/KT transporters, shaker type K+ transporters, and K+ efflux antiporters. Besides the ion transport process, we have shed light on available literature on epigenetic regulation of transport processes under salt stress. Recent advancements of salt stress sensing mechanisms and various salt sensors within signaling transduction pathways are discussed. Further, we have compiled salt‐stress signaling pathways, and their crosstalk with phytohormones.

Root Na+ Content Negatively Correlated to Salt Tolerance Determines the Salt Tolerance of Brassica napus L. Inbred Seedlings

“…Many advances have been made in the study of ion transporters in plant salt tolerance. During exposure to salt stress, the salt overly sensitive (SOS) pathway is known to play a vital role in plants, and the exploration of salt stress perception, signal transduction pathways and regulatory mechanisms are all related to this [ 20 , 21 , 86 , 87 ]. The main components of this pathway are a plasma membrane Na + /H + antiporter (SOS1), a Ser/Thr protein kinase (SOS2), and a Ca 2+ -binding protein (SOS3) [ 26 , 88 , 89 ].…”

Ammonium and nitrate affect sexually different responses to salt stress in Populus cathayana

“…Aquaporin PIP1 ; 1 and PIP2 ; 1 were downregulated, but PIP1 ; 4 and TIP2 ; 1 were upregulated under salt stress in females under both N forms (Figure 7A,B). Aquaporin facilitates the regulation of water balance and increases salt tolerance in plants (Saddhe et al, 2021; Sreedharan et al, 2015). In contrast, the upregulation of genes encoding aquaporin PIP2 ; 7 and TIP1 : 1 was greater in males than in females, suggesting that males have a sophisticated regulation of water transport, which also enhances salt stress tolerance.…”

Plant Salinity Sensors: Current Understanding and Future Directions

“…In Arabidopsis, OSCA1 is a high osmotic stress–gated Ca 2+ channel protein that is also considered as an osmotic stress sensor ( Yuan et al, 2014 ; Zhai et al, 2020 ). Ca 2+ -responsive phospholipid-binding BONZAI (BON) proteins play an important role in regulating all osmotic stress responses and are considered a kind of sensor in the membrane ( Chen et al, 2020 ; Saddhe et al, 2021 ). In addition, the Proline Porter (ProP) in Escherichia coli , which responds to osmotic stress by transporting H + and a variety of osmo-protective organic substances into the cell, is considered to be an osmosensor ( Sayeed and Baenziger, 2009 ).…”

“…Primary salt-stress sensors (i.e., those recognizing osmotic or ionic stress) may include pectins in the cell wall, plasma membrane lipids such as glycosyl inositol phosphorylceramide (GIPC), and plasma membrane proteins such as receptor-like kinases (RLKs), protein kinases, and ion transporters, etc. However, besides the identification of the Na + receptor GIPC, little progress has been made in identifying salt-stress sensors ( Yang and Guo, 2018 ; Jiang et al, 2019 ; Yu et al, 2020 ; Saddhe et al, 2021 ; Chaudhry et al, 2022 ), because complete knockouts of the corresponding genes are either lethal or produce no change in phenotype due to functional redundancy. Another challenge is that roots, which are the first plant organ to encounter the salinity stress, are more difficult to study than shoots.…”