Leymus chinensis is important for ecological restoration and stock farming in Eurasia. In the context of climate change, excavating L. chinensis germplasm resources with excellent ecological functional traits is important to resist grassland degradation and promote the restoration of degraded grassland ecosystems. In this study, we used 42 L. chinensis germplasm resources (LC01–LC42) from different geographical sources to perform a multidimensional comprehensive evaluation of drought tolerance, rhizome space expansion, and soil improvement abilities. (1) LC07, LC15, LC18, and LC19 exhibited excellent ecological functional traits and could be used in breeding for ecological restoration. They were mainly from eastern and central Mongolia and central Inner Mongolia. (2) Principal component analysis showed that eight principal components with eigenvalues ≥1 were extracted from 26 traits of L. chinensis. The cumulative contribution rate was 80.551%. (3) There was a significant positive correlation between the F value and longitude and a significant negative correlation of the F value with latitude. L. chinensis germplasms from high longitudes and low altitudes may exhibit better comprehensive performance. (4) Plant height, leaf number, tiller number, malonaldehyde, chlorophyll content, dry weight on the ground, maximum one-direction extended distance, and organic matter can be used as key indices to comprehensively evaluate L. chinensis germplasm resources.

Climate change related abiotic stress has been potentially impacting the quantity and quality of forage grass. Melatonin, a multifunctional molecule that has been found to be present in all plants examined to date, plays a crucial role in improving forage grass tolerance to both biotic and abiotic stresses. However, research on melatonin’s role in forage grass is still developing. In this review, the effects of melatonin application on abiotic stress are the primary topic, and we try to find relative mechanisms. In order to determine whether melatonin has a good effect on forage grass, we compared and summarized the adapting ability of different forage grasses under abiotic stress after melatonin application in aspects of growth and development, photosynthesis, antioxidant systems, plant hormone interactions, and ion homeostasis. According to part of the data, we found that different forage grasses exhibited varying responses to endogenous melatonin content and exogenous melatonin dose applications. Meanwhile, the regulatory mechanisms of melatonin application include the expression of chlorophyll synthesis and degradation genes, electron transport and phosphorylation genes, stress regulation pathway genes, and plant hormone synthesis genes. We propose possible future studies that can further explore the metabolic pathways of melatonin and the molecular mechanisms of melatonin regulation of abiotic stress in forage grass. Specifically, research can focus on elucidating the signaling pathways, gene expression of regulatory networks, and interactions with other plant hormones. This will provide valuable theoretical and practical guidance for adapting to climate change and forage grass development.

Grassland plants that endure livestock grazing exhibit a dwarf phenotype, which can be transmitted to clonal offspring. Yet to date, it remains poorly understood whether such transgenerational dwarf effects alter the plants’ response to shade. Here, we conducted a common garden experiment under sunlight and shade conditions with clonal Leymus chinensis offspring, the parents of which had endured livestock overgrazing (OG) and non-grazing (NG) in the field, respectively. Plant morphological, physiological, and transcriptomic analyses were carried out. The results indicated that NG offspring showed greater shade avoidance than OG offspring. That is, NG offspring exhibited greater plasticity of vegetative height and leaf width, which may be contributed to their greater photosynthetic capacity and gibberellin (GA3) content compared with OG offspring when treated with shade. In addition, RNA-Seq profiling showed that differentially expressed genes in NG offspring were mainly enriched in RNA modification and metabolic processes, which facilitated rapid response to shade. Phytochrome interacting factors (PIFs) promoted downstream shade marker genes in NG offspring by significantly downregulating the expression of PHYC, SPY, and DELLA. Our findings suggest that light conditions should be taken into account to better understand transgenerational dwarf effects induced by livestock grazing on grassland ecosystems. These results provide new insights into the inducible factors of phenotypic variations in grassland plants that experience grazing.

Leymus chinensis (Trin.) Tzvel., a vital native forage grass in northern China for ecological restoration and livestock production, faces severe yield losses and grassland degradation due to rust (Puccinia spp.) infection. Current control strategies, reliant on chemical interventions, are limited by evolving resistance risks and environmental concerns, while rust-resistant breeding remains hindered by insufficient molecular insights. To address this, we systematically evaluated rust resistance in 24 L. chinensis germplasms from diverse geographic origins, identifying six highly resistant (HR) and five extremely susceptible (ES) genotypes. Integrating transcriptomics and metabolomics, we dissected molecular responses to Puccinia infection, focusing on contrasting HR (Lc71) and ES (Lc5) germplasms at 48 h post-inoculation. Transcriptomic analysis revealed 1012 differentially expressed genes (DEGs: 247 upregulated, 765 downregulated), with enrichment in cell wall biosynthesis and photosynthesis pathways but suppression of flavonoid synthesis. Metabolomic profiling identified 287 differentially accumulated metabolites (DAMs: 133 upregulated, 188 downregulated), showing significant downregulation of pterocarpans and flavonoids in HR germplasms, alongside upregulated cutin synthesis-related metabolites. Multi-omics integration uncovered 79 co-enriched pathways, pinpointing critical regulatory networks: (1) In the nucleotide metabolism pathway, genes Lc5Ns011910, Lc1Xm057211, and Lc4Xm043884 exhibited negative cor-relations with metabolites Deoxycytidine and Cytosine. (2) In flavonoid biosynthesis, Lc2Xm054924, Lc4Xm044161, novel.8850, Lc2Ns006303, and Lc7Ns021884 were linked to naringenin and naringenin-7-O-glucoside accumulation. These candidate genes likely orchestrate rust resistance mechanisms in L. chinensis. Our findings advance the molecular understanding of rust resistance and provide actionable targets for breeding resilient germplasms.