Soil Salinity, a Serious Environmental Issue and Plant Responses: A Metabolomics Perspective

Abstract

The effects of global warming have increasingly led to devastating environmental stresses, such as heat, salinity, and drought. Soil salinization is a serious environmental issue and results in detrimental abiotic stress, affecting 7% of land area and 33% of irrigated lands worldwide. The proportion of arable land facing salinity is expected to rise due to increasing climate change fuelled by anthropogenic activities, exacerbating the threat to global food security for the exponentially growing populace. As sessile organisms, plants have evolutionarily developed mechanisms that allow ad hoc responses to salinity stress. The orchestrated mechanisms include signalling cascades involving phytohormones, kinases, reactive oxygen species (ROS), and calcium regulatory networks. As a pillar in a systems biology approach, metabolomics allows for comprehensive interrogation of the biochemistry and a deconvolution of molecular mechanisms involved in plant responses to salinity. Thus, this review highlights soil salinization as a serious environmental issue and points to the negative impacts of salinity on plants. Furthermore, the review summarises mechanisms regulating salinity tolerance on molecular, cellular, and biochemical levels with a focus on metabolomics perspectives. This critical synthesis of current literature is an opportunity to revisit the current models regarding plant responses to salinity, with an invitation to further fundamental research for novel and actionable insights.

Integrated metabolomic and transcriptomic analysis reveals the role of phenylpropanoid biosynthesis pathway in tomato roots during salt stress

“…Soil salinization is a land degradation process that restricts plant growth and grain yield and has become a global problem that continues to deteriorate ( Yuan et al., 2016 ; Landi et al., 2017 ; Gu et al., 2022 ). Currently, besides the original salinized soils, which account for at least 7% of the world’s entire land area, irrigated lands and agricultural lands are increasingly subject to salinization, and their affected area is expected to double by 2050 ( Rengasamy, 2006 ; Chele et al., 2021 ). At this point, grain production is required to increase by 70-110% to largely satisfy the food requirement of the rapidly growing global population ( Tilman et al., 2011 ; Butcher et al., 2016 ; Molotoks et al., 2020 ).…”

Structure, Function, and Regulation of the Plasma Membrane Na+/H+ Antiporter Salt Overly Sensitive 1 in Plants

“…After plants quickly perceive changes in the external environment, they will produce secondary messengers, such as Ca 2+ , inositol phosphate, ROS, and plant hormones in the cytoplasm, and salt stress signal are further decoded and amplified in a stepwise fashion ( Xiong et al, 2002 ; Xiong and Zhu, 2002 ; Zhu, 2016 ). This signal cascade involves perception and binding of Ca 2+ by calmodulin, protein phosphorylation and dephosphorylation, and phospholipid metabolism ( Hashimoto and Kudla, 2011 ; Chele et al, 2021 ). Furthermore, the final targets of these cascades may be specific transcription factors that further activate the expression of genes related to salt stress.…”

Metabolomics and Chemoinformatics in Agricultural Biotechnology Research: Complementary Probes in Unravelling New Metabolites for Crop Improvement

“…PLS-DA and its extensions such as orthogonal PLS-DA (OPLS-DA) and sparse PLS-DA (sPLS-DA) describe the most significant variance to differentiate between practical classes to decipher the metabolic features that are most significant to the observed classification [ 52 , 55 ]. OPLS-DA is a binary classifier that uses two experimental group systems to compare metabolic features (generally treated vs. untreated samples); from this, metabolites with an enormous impact on the projection are selected and termed significant metabolic markers responsible for the differences in metabolic features from the two experimental groups under investigation [ 56 , 57 ].…”

“…The strategies for mitigating the impacts of salinity stress in plants span the primary and secondary metabolism, reflecting the basal work conducted at the genome level. The primary metabolism is pivotal in regulating salinity stress responses; essential roles have been suggested, including energy production for the initial cost of stress-related metabolic response mechanisms, the activation and regulation of signaling cascades, and the provision of substrates for secondary metabolism [ 57 ]. In contrast, the secondary metabolism provides specialized metabolites that facilitate the salinity stress response through such mechanisms as antioxidant synthesis pathways for ROS scavenging and the reduction of oxidative damage [ 57 , 86 ].…”

“…The primary metabolism is pivotal in regulating salinity stress responses; essential roles have been suggested, including energy production for the initial cost of stress-related metabolic response mechanisms, the activation and regulation of signaling cascades, and the provision of substrates for secondary metabolism [ 57 ]. In contrast, the secondary metabolism provides specialized metabolites that facilitate the salinity stress response through such mechanisms as antioxidant synthesis pathways for ROS scavenging and the reduction of oxidative damage [ 57 , 86 ]. A recent Fourier transform mass spectrometry LTQ orbitrap (FTMS)-based metabolomics study by Sarri and colleagues [ 89 ] found that secondary metabolites from saponins and hydroxycinnamic acids play a significant role in increased salinity-stress tolerance in Medicago sativa and Medicago arborea species.…”