Salt stress severely inhibits plant growth. Understanding the mechanism of plant salt tolerance is highly important to improving plant salt tolerance. Previous studies have shown that nonselective cyclic nucleotide-gated ion channels (CNGCs) play an important role in plant salt tolerance. However, current research on CNGCs mainly focuses on CNGCs in glycophytic plants, and research on CNGCs in halophytes that exhibit special salt tolerance strategies is still scarce. This study used the halophilic plant Zoysia japonica, an excellent warm-season turfgrass, as the experimental material. Through bioinformatics analysis, 18 members of the CNGC family were identified in Zoysia japonica; they were designated ZjCNGC1 through ZjCNGC18 according to their scaffold-level chromosomal positions. ZjCNGCs are divided into four groups (I–IV), with the same groups having differentiated protein-conserved domains and gene structures. ZjCNGCs are unevenly distributed on 16 scaffold-level chromosomes. Compared with other species, the ZjCNGCs in Group III exhibit obvious gene expansion, mainly due to duplication of gene segments. The collinearity between ZjCNGCs, OsCNGCs, and SjCNGCs suggests that CNGCs are evolutionarily conserved among gramineous plants. However, the Group III ZjCNGCs are only partially collinear with OsCNGCs and SjCNGCs, implying that the expansion of Group III ZjCNGC genes may have been an independent event occurring in Zoysia japonica. Protein interaction prediction revealed that ZjCNGCs, calcium-dependent protein kinase, H⁺-ATPase, outwardly rectifying potassium channel protein, and polyubiquitin 3 interact with ZjCNGCs. Multiple stress response regulatory elements, including those involved in salt stress, are present on the ZjCNGC promoter. The qPCR results revealed differences in the expression patterns of ZjCNGCs in different parts of the plant. Under salt stress conditions, the expression of ZjCNGCs was significantly upregulated in roots and leaves, with ZjCNGC8 and ZjCNGC13 showing the greatest increase in expression in the roots. These results collectively suggest that ZjCNGCs play an important role in salt tolerance and that their expansion into Group III may be a special mechanism underlying the salt tolerance of Zoysia japonica.

This study was designed to investigate the relationship between the caloric value and salt tolerance of two varieties of Miscanthus sacchariflorus (Amur silvergrass: M127 and M022). The salt tolerance capacity, photosynthetic characteristics, Na⁺ and K⁺ uptake by the roots and aboveground parts, and caloric value of different parts of the aboveground parts were obtained under hydroponic conditions. The results showed that M022 was more tolerant to salt stress than M127 and the former had a higher photosynthetic efficiency as well as a lower aboveground Na⁺ accumulation, K⁺ efflux, and larger K⁺/Na⁺ ratio. The calorific values of stems, spear leaves, aging leaves, and functional leaves of the two varieties showed a decreasing trend with increasing NaCl concentration. At 270 mM NaCl, the calorific values of the stems, aging leaves, functional leaves, and spear leaves was reduced by 18.10%, 46.73%, 26.11%, and 18.35% for M022 and 41.99%, 39.41%, 34.82%, and 45.09% for M127 compared to the controls, respectively. We observed that the aging leaves of M022 had a faster decline rate in calorific value than those of M127, indicating that the aging leaves of M022 preferentially isolated the harmful Na⁺ ion, reduced its accumulation in other parts, and increased the K⁺/Na⁺ ratio in the corresponding parts, thus inhibiting the decrease in calorific value. Following this result, it can be inferred that M022 inhibited the decline in calorific values during stress by efficiently compartmentalizing the distribution of Na⁺ and K⁺. Our results provide a theoretical basis and technical support for the efficient cultivation of salt-tolerant energy plants in saline–alkaline soil.

As one of the most salt-tolerant grasses, characterizing salt-tolerance genes of Zoysia matrella [L.] Merr. not only broaden the theoretical information of salt tolerance, but also provide new salt-resistant genetic resources for crop breeding. The salt-inducible protein disulfide isomerase (ZmPDI) of Zoysia matrella [L.] Merr. was proved to enhance salt tolerance in homologous overexpression transgenic plants. In order to evaluate its potential application in crops, we conducted the salt tolerance evaluation in heterologous overexpression transgenic rice (OX-ZmPDI), Wild-type (WT) rice, and LOC_Os11g09280 (OsPDI, homologous gene of ZmPDI in rice) knock-out rice generated by CRISPR-Cas9 system (CR-OsPDI). Our findings revealed that OX-ZmPDI rice was higher and exhibited longer main root length, more proline (Pro) and malondialdehyde (MDA), and higher peroxidase (POD) activity than WT control after salt treatment, while CR-OsPDI resulted in contrary phenotypes. These results indicated that ZmPDI can significantly enhance the salt tolerance in rice, whereas loss-of-function of OsPDI reduces the salt tolerance. To further investigate these differences at the molecular level, we collected roots from OX-ZmPDI transgenic, CR-OsPDI transgenic, and wild-type (WT) plants at 0 and 24 h after salt treatment for RNA-seq and data-independent acquisition (DIA) proteome sequencing. Combined analysis of the transcriptome and proteome revealed that ZmPDI has the potential to enhance the salt tolerance of rice by modulating the expression of laccase-6, zingipain-2, WIP3, FKBP65, AKR4C10, GBSSII, Pho1, and TRXf1. Those results provided new information for the molecular regulation mechanism by which ZmPDI improves salt tolerance, and prove the potential of ZmPDI for application in crop breeding.

Owing to the poor cold tolerance of Stenotaphrum Trin and the urgent need for shade-tolerant grass species in temperate regions of East China, this study evaluated the cold tolerance of 55 Stenotaphrum accessions, aiming to provide shade-tolerant materials for temperate regions. A fine cold-tolerant turfgrass should have both the advantages of delayed fall dormancy and early spring green-up. However, previous research on the cold resistance of turfgrass has mainly focused on the performance of the spring green-up, with less attention paid to the fall dormancy, which has affected the ornamental and application value of turfgrass. This study first dynamically investigated the leaf colour of each accession during the fall dormancy and the coverage during the spring green-up and evaluated the cold resistance of the accession through membership functions and cluster analysis. Significant differences in the cold resistance were found with the assignment of breeding lines to four categories. The weak correlation (R² = 0.1682) between leaf colour during the fall dormancy and coverage during the spring green-up indicates that using the performance of a single period to represent the cold resistance of accessions is not appropriate. To test whether using the laboratory-based LT50 and stolon regrowth rating analysis can replace the above-improved method, we conducted a related analysis and found that the fit between these two methods is very poor. This phenomenon is attributed to the poor correlation between the laboratory-based parameters and the pot-investigated data. Therefore, this study presents a cold resistance evaluation method for Stenotaphrum that integrates performance in both the fall dormancy and spring green-up periods. This improved evaluation method cannot be simplified by the growth performance of a single period or replaced by using laboratory-based LT50 and stolon regrowth tests. With the help of this improved method, several excellent cold tolerance accessions (ST003, S13, and S12) were identified for temperate regions of East China.

Salt stress inhibits plant growth, requiring salt-tolerant genes for the development of resilient plants. A key tolerance mechanism is potassium/sodium homeostasis, governed by Shaker K⁺ channels. Given that Shaker K⁺ channels from salt-sensitive species have been extensively studied while their counterparts in salt-tolerant plants remain largely unexplored, this study investigates the evolution and function of these channels in salt-tolerant bermudagrass to address this knowledge gap. Genomic analysis identified 25 Shaker K⁺ channel genes, an expanded family relative to other species. Phylogenetics placed them into five groups (I–V), with groups I, II, III, and V expanded via segmental duplication. Salt stress response screening revealed that only CdKAT1.1 was rapidly upregulated. Functional assays in yeast demonstrated that both CdKAT1.1 and its closest homolog CdKAT1.2 improve potassium uptake and salt tolerance, but the enhancement from CdKAT1.1 was significantly greater. This work elucidates the expansion and functional divergence of Shaker K⁺ channels in bermudagrass. CdKAT1.1 emerges as a superior regulator of potassium efficiency and salt tolerance, making it a prime candidate for molecular breeding to improve plant resilience in saline-alkaline soils.

Screening for stomatal opening enhancers and their application via foliar spraying represents a feasible strategy to increase CO₂ assimilation flux by augmenting stomatal aperture, thereby enhancing photosynthesis and promoting plant growth. However, the lack of relevant research on forage crops has significantly limited the implementation of this strategy in forage production. In this study, using vetch (Vicia sativa) and alfalfa (Medicago sativa) as experimental materials, we first established a stable observation system tailored for evaluating stomatal opening regulation in forages: incubating abaxial epidermal peels in a solution containing 0.5% KCl (pH 6.0) under light conditions for 4 h resulted in stably opened stomata. Utilizing this system, we systematically screened the regulatory effects of 14 stomatal opening modulators, including signaling molecules, phytohormones, and amino acids. The results indicated that stomatal opening in both vetch and alfalfa exhibited pronounced concentration-dependent and species-specific responses to the modulators. Supplementation with appropriate concentrations of EGTA, GA₃, MT, His, and Pro significantly promoted stomatal opening in vetch, with increases ranging from 21% to 35%. In contrast, appropriate concentrations of Ca²⁺, H₂O₂, MJ, His, Glu, Met, Arg, and Ala effectively enhanced stomatal opening in alfalfa, with increases of 8% to 34%. To further validate the reliability of the screening system, we selected Met, which showed no regulatory effect on vetch stomata but enhanced opening in alfalfa, for foliar application validation. The results demonstrated that Met treatment had no significant effect on stomatal aperture in vetch but significantly increased it in alfalfa, consistent with the initial screening results. This consistency further confirmed the reliability of our established screening system for identifying stomatal opening enhancers in forages. Correspondingly, foliar Met application did not affect vetch growth but significantly promoted alfalfa growth, increasing biomass by 18%. In conclusion, this study established a stable screening system for stomatal opening enhancers specifically for vetch and alfalfa and successfully identified several species-specific enhancers using this system. Foliar application of these species-specific enhancers effectively increased stomatal aperture and promoted growth in target forage species, demonstrating promising potential for enhancing forage yield.