Physiological and transcriptomic analysis of salt tolerant Glaux maritima grown under high saline condition.

Land salinization considerably limits crop production. Biological improvement of saline and alkaline land is an important way to achieve efficient land use. It is crucial to study the salt tolerance of halophyte resources in order to explore and improve plant resources through biological improvement. Glaux maritima is a mesophyte halophyte with strong salt tolerance. In this study, we conducted research on the salt tolerance mechanism of G. maritima through phenotypic, physiological, and transcriptomic aspects. The results indicate that leaf cross-sections revealed that G. maritima has a salt gland tissue composed of stalk, collecting, and secretory cells, which are trapped in epidermal cells. At the physiological level, the maximum salt tolerance threshold of G. maritima leaves was 600 mM/L. At this concentration, proline content, relative conductivity, and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities were maximum. At the transcriptional level, transcriptome data of three experimental groups (N0: 0 mM/L, N3: 600 mM/L, and N4: 800 mM/L) were analyzed, and six essential genes related to proline synthesis and five essential genes related to SOD and CAT enzyme activities were identified. Two genes involved in CAT enzyme activity were also found to play an important role in the MAPK signaling pathway. Trend analysis revealed that the MAPK signaling regulation (37 differentially expressed genes (DEGs)), phytohormone regulation (48 DEGs), glutathione metabolism (8 DEGs), flavonoid and flavonoid biosynthesis (2DEGs), and flavonoid biosynthesis (24 DEGs) pathways played important roles in regulating the salt tolerance of G. maritima. These findings provide valuable information for further studies on the functional characteristics of G. maritima in response to abiotic stress and may contribute to salt resistance breeding of fodder crops for cultivation in saline alkali land.

[Effects of cutting on the dominant and subdominant plant species in a Stipa krylovii steppe of Inner Mongolia].

Based on the long-term cutting experiment, this paper analyzed the responses of the aboveground biomass of five dominant and subdominant plant species and the community stability in a Stipa krylovii steppe of Inner Mongolia to various cutting height. Cutting with a stubble height of > 10 cm had slight effects on the aboveground biomass of the five species. Cutting with a stubble height of 10 cm benefited the growth of Artemisia frigida but made against the growth of Stipa krylovii. Cleistogenes squarrosa at the stubble height of 2 cm performed best, and Carex korshinskyi at the stubble height of 5 cm contributed most to the community, with the biomass positively correlated with the cutting years. Potentilla acaulis growth was detrimentally affected at the stubble heights of 2 and 15 cm. Overall, perennial species with higher plant height and stronger competitive ability were more tolerant to disturbances, and a minimum cutting height of 10 cm should be applied to maintain a high stability of the steppe ecosystem.