Salinity Induces Allometric Accumulation of Sulfur in Plants and Decouples Plant Nitrogen‐Sulfur Correlation in Alpine and Arid Wetlands

Abstract

Salinization alters the elemental balance of wetlands and induces variations in plant survival strategies. Sulfur (S) plays vital roles in serving regulatory and catalytic functions in stress resistance of plants. Yet, how plant S and its relationships with nitrogen (N) vary across natural environmental gradients are not well documented. We collected 1,366 plant samples and 230 water and sediment samples from 230 wetlands in Tibetan Plateau and adjacent arid regions of western China, to analyze the effects of environmental variables on plant S accumulation and N‐S correlations. We found that plant S correlated with N in unimodal patterns. Salinity, rather than temperature or nutrient supply, promoted disproportionate accumulation of S but limited N uptake, inducing decoupling of N‐S correlation in plants. Toward high salinity, the faster increasing rates of total S than that of glutathione, the most abundant organic‐S compound in plant resistance, provided potential evidences explaining the decoupled plant N‐S correlation. A salinity of 3.9‰ was calculated to be a threshold at which substantial changes in plant N‐S correlation occurred. We designed a conceptual model to illustrate the mechanisms driving variations of N‐S correlation in plants and environments along salinity gradient. Furthermore, high salinity filtered out the salt‐sensitive species and reassembled the communities. In conclusion, increased salinity affected wetland plants by inducing S accumulation in plants and selecting salt‐tolerant species with high S concentrations at community level, providing evidences for plant adaptive mechanisms to salinity in arid regions.

Global leaf sulfur stoichiometry and the relationships with nitrogen and phosphorus: phylogeny, growth form and environmental controls

“…Similarly, relatively lower LS concentrations in our study were caused by the high proportion of gymnosperms (mainly conifers), because gymnosperms contained the minimum LS concentrations of all phylogenetic taxa and thus pulled down the mean values of woody plants (table 1). The herbaceous species, especially aquatic plants, had the highest LS concentrations in all growth forms, verifying the crucial role of S in stress tolerance, because most of the aquatic plant species were collected from saline habitats in the Tibetan Plateau and arid and semi-arid regions in northwest China [25].…”

“…Therefore, S concentrations and the correlations of S to N and P in plants should be species-specific, which are largely determined by the physiological requirements of plants and vary among species [18,19]. The variations in plant S-N-P stoichiometries can be attributed to the differences in plant taxa, as well as the local elemental conditions in environments, as demonstrated by the regional studies [12,14,[25][26][27]. However, compared with the well-documented leaf N-P stoichiometry, the globally stoichiometric patterns of plant leaf S concentrations and their relationships to N and P are less studied.…”

“…S is absorbed mainly in the form of sulfate (SO 4 2− ) and is synthesized into a wide variety of S-containing compounds, for example, amino acids (cysteine and methionine), oligopeptides (glutathione and phytochelatins), vitamins, cofactors and various secondary products, taking the job of antioxidative, catalytic and defensive functions and so on [17,19,22]. Physiologically, S and N are taken up by plant roots with similar strategies [23], assimilated in well-coordinated pathways and tightly coupled with each other [24,25]. Therefore, S concentrations and the correlations of S to N and P in plants should be species-specific, which are largely determined by the physiological requirements of plants and vary among species [18,19].…”

Genomic analysis of the emergent aquatic plant Sparganium stoloniferum provides insights into its clonality, local adaptation and demographic history

“…Among these local adaptation genes, we further identified 33 genes under positive selection involved in abiotic stress response and plant growth and development in the NW and SW lineages (Table S17). The NW lineage is distributed in Northwest China in areas with numerous saline wetlands due to low precipitation and high evaporation together with saline soil parent materials (Zuo et al, 2022); the SW lineage is mainly found Southwest China in an environment characterized by high altitude. The identified PSGs may be related to the response of the NW and SW lineages to their environmental conditions.…”