Plants cope with abiotic stress in several ways, including by collaborating with microorganisms. Epichloë, an endophytic fungus, has been shown to improve plant tolerance to extreme external environments. Hordeum bogdanii is a known salt-tolerant plant with the potential to improve alkaline lands. NHX1 plays a key role in the transport of ions in the cell and is overexpressed in plants with increased salt tolerance. However, the expression levels of HbNHX1 in Epichloë endophytic fungal symbionts in H. bogdanii have not been elucidated. We used Hordeum bogdanii (E+) with the endophytic fungi Epichloë bromicola and H. bogdanii (E−) without the endophytic fungi and compared the differences in the ion content and HbNHX1 expression between the shoots and roots of E+ and E− plants under alkaline stress. The absorption capacity of both K⁺ and Na⁺ of H. bogdanii with endophytic fungi was higher than that without endophytic fungi. In the absence of alkaline stress, endophytic fungi significantly reduced the Cl⁻ content in the host H. bogdanii. Alkaline stress reduced SO₄²⁻ content in H. bogdanii; however, compared with E−, endophytic fungi increased the content of SO₄²⁻ in E+ plants. With an increase in the alkaline concentration, the expression of HbNHX1 in the roots of H. bogdanii with endophytic fungus exhibited an upward trend, whereas the expression in the shoots exhibited a downward trend first and then an upward trend. Under 100 mmol·L⁻¹ mixed alkaline stress, the expression of HbNHX1 in E+ was significantly higher than that in E−, indicating that endophytic fungi could increase the Na⁺ region in vacuoles. The external environment affects the regulation of endophytic fungi in H. bogdanii and that endophytic fungi can play a key role in soil salinization. Therefore, the findings of this study will provide technical support and a theoretical basis for better utilization of endophytic fungi from H. bogdanii in saline land improvement.

Fungal endophytes are symbiotic microorganisms that establish strong relationships inside plant tissues, providing potential advantages, especially in grasses, by enhancing tolerance to both abiotic and biotic stresses. This review investigates the molecular mechanisms through which fungal endophytes mediate stress tolerance, targeting host–pathogen interactions. By modulating pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and effector proteins, fungal endophytes may contribute to priming the plant’s immune system, enhancing its resistance to pathogen invasion. Moreover, endophyte colonization regulates core processes such as osmotic regulation, reactive oxygen species (ROS) detoxification, and secondary metabolite biosynthesis that enable plants to tolerate environmental stresses like drought, heat, and salinity. The review highlights the impact of endophytes on immune priming, systemic acquired resistance (SAR), and the regulation of non-coding RNAs that regulate host gene networks associated with stress tolerance. Furthermore, the integration of advanced multi-omics techniques genomics, transcriptomics, proteomics, metabolomics, and fluxomics has revealed emerging insights into the genetic and metabolic pathways driving these symbiotic associations. However, grass-specific molecular datasets remain limited, and the consistency of endophyte-mediated tolerance across host species and environmental conditions is not yet fully resolved. Fungal endophytes increase grass stress resilience through coordinated pathogen recognition, RNA regulation, and metabolic reprogramming while AI-assisted multi-omics approaches are emerging as tools for identifying candidate regulatory networks, although empirical validation in grass–endophyte systems remains limited. Together, these advances highlight the potential for climate-smart and sustainable crop improvement. Future research integrating functional genomics, field validation, and biosafety assessment will be essential for translating endophyte-based strategies into reliable agricultural applications.

Botanical gardens are highly heterogeneous plant systems characterized by high taxonomic diversity, with numerous plant taxa represented within confined areas, and complex ecological interactions that create unique challenges for pest management. Conventional IPM strategies, designed for simplified agroecosystems, often fail to address complex pest pressures in curated environments. Microbial biostimulants have emerged as promising components of sustainable IPM strategies by enhancing plant defense responses, improving stress resilience, and reducing reliance on chemical inputs. This review synthesizes current knowledge on microbial biostimulants, including plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi and endophytic microorganisms, in modulating plant defense against insect herbivores. These beneficial microbes enhance plant resistance through multiple mechanisms. They activate induced systemic resistance and modulate key phytohormones, including jasmonic acid, salicylic acid, and ethylene. Additionally, they regulate calcium-dependent and reactive oxygen species-mediated defenses. Microbially induced changes in plant secondary metabolites and volatile organic compounds further influence herbivore behavior and trophic interactions. Emphasis is placed on integrating microbial biostimulants into IPM frameworks tailored to botanical gardens. This highlights compatibility with biological control agents and reduced reliance on synthetic pesticides. Despite promising advances, challenges remain, including context-dependent efficacy, host specificity and limited long-term validation. Overall, microbial biostimulants offer a promising tool for enhancing IPM in biodiversity-rich botanical gardens, although further long-term validation is needed to fully assess their sustainability and effectiveness.

Background/Objectives: Antimicrobial peptides (AMPs) contribute to plant innate immunity and abiotic-stress adaptation, but their repertoires remain poorly characterized in extremophytic plants. We aimed to define AMP gene families and their expression under Na₂SO₄ treatment in the xerophytic recretohalophyte Reaumuria soongarica. Methods: Six canonical AMP families were screened using hidden Markov model and homology searches, domain verification, gene-model and transcript-support assessment, nsLTP boundary curation, phylogenetic and synteny analyses, and reanalysis of public RNA-sequencing data from 0, 200, and 400 mM Na₂SO₄ treatments. Results: We identified 73 candidates: 15 defensins, 18 Snakin/GASA genes and 40 nsLTPs, including seven previously unannotated, transcript-supported models. RsLTP20 was reported separately as a reference-dependent C4-like candidate. Four sequence and alignment strategies supported two defensin, one Snakin/GASA and three nsLTP local groups. No tested promoter pattern was significantly enriched after multiple-testing correction. At 400 mM Na₂SO₄ relative to the control, 18 of the 66 catalogue members represented in the quantification reference were differentially expressed (12 upregulated and six downregulated; BH-adjusted p < 0.05 and |log₂ fold change| > 1). Comparison with 38 Tamarix austromongolica candidates identified 27 reciprocal-best-hit pairs; genomic collinearity supported 25 direct candidate pairs. A separate Arabidopsis comparison recovered 26 candidate-anchored pairs. Conclusions: This curated catalogue defines conservative phylogenetic groups and provides candidates for experimental analysis of stress adaptation and peptide function.