The germin-like protein (GLP) family plays vital roles for plant growth, stress adaptation, and defense; however, its evolutionary dynamics and functional diversity in halophytes remain poorly characterized. Here, we present the genome-wide analysis of the GLP family in the halophytic forage alkaligrass (Puccinellia tenuiflora), which identified 54 PutGLPs with a significant expansion compared to other plant species. Phylogenetic analysis revealed monocot-specific clustering, with 41.5% of PutGLPs densely localized to chromosome 7, suggesting tandem duplication as a key driver of family expansion. Collinearity analysis confirmed evolutionary conservation with monocot GLPs. Integrated gene structure and motif analysis revealed conserved cupin domains (BoxB and BoxC). Promoter cis-acting elements analysis revealed stress-responsive architectures dominated by ABRE, STRE, and G-box motifs. Tissue-/organ-specific expression profiling identified root- and flower-enriched PutGLPs, implying specialized roles in stress adaptation. Dynamic expression patterns under salt-dominated stresses revealed distinct regulatory pathways governing ionic and alkaline stress responses. Functional characterization of PutGLP37 demonstrated its cell wall localization, dual superoxide dismutase (SOD) and oxalate oxidase (OXO) enzymatic activities, and salt stress tolerance in Escherichia coli, yeast (Saccharomyces cerevisiae INVSc1), and transgenic Arabidopsis. This study provides critical insights into the evolutionary innovation and stress adaptive roles of GLPs in halophytes.

Maize, as a glycophyte, is hypersensitive to salinity, but the salt response mechanism of maize remains unclear. In this study, the physiological, biochemical, and molecular responses of two contrasting inbred lines, the salt-tolerant QXH0121 and salt-sensitive QXN233 lines, were investigated in response to salt stress. Under salt stress, the tolerant QXH0121 line exhibited good performance, while in the sensitive QXN233 line, there were negative effects on the growth of the leaves and roots. The most important finding was that QXH0121 could reshift Na⁺ from shoots into long roots, migrate excess Na⁺ in shoots to alleviate salt damage to shoots, and also improve K⁺ retention in shoots, which were closely associated with the enhanced expression levels of ZmHAK1 and ZmNHX1 in QXH0121 compared to those in QXN233 under salt stress. Additionally, QXH0121 leaves accumulated more proline, soluble protein, and sugar contents and had higher SOD activity levels than those observed in QXN233, which correlated with the upregulation of ZmP5CR, ZmBADH, ZmTPS1, and ZmSOD4 in QXH0121 leaves. These were the main causes of the higher salt tolerance of QXH0121 in contrast to QXN233. These results broaden our knowledge about the underlying mechanism of salt tolerance in different maize varieties, providing novel insights into breeding maize with a high level of salt resistance.

Inorganic phosphate (Pi) deficiency is a main limiting factor on crops growth and to select low-Pi tolerant breeding lines is very significant for crop breeding. Here, two contrasting maize (Zea maysL.) breeding lines showed different physiological response to Pi deficiency. The low-Pi tolerant QXN233 maintained normal growth, including high fresh weight, green leaves, strong shoots, and numerous roots relative to that of the sensitive MH05-4, mainly due to QXN233’ high Pi content in shoots under Pi deficiency. Importantly, some Pi-responsive genes were detected, and among them, Pi transportersZmPHT1;1andZmPHT1;9as well as phytase geneZmphytase 2were expressed increasingly in QXN233 compared to MH05-4 under Pi deprivation or Pi resupply. Moreover, QXN233 had higher proline content, soluble sugar content, and SOD activity than MH05-4, related with its tolerance. Taken together, this study enriches the understanding of the mechanism of maize responding to Pi deficiency.

Acyl-CoA-binding proteins (ACBPs) possess a conserved acyl-CoA-binding (ACB) domain that facilitates binding to acyl-CoA esters. In addition to their typical role in lipid metabolism, plant ACBPs have been shown to participate in various physiological processes, such as membrane biogenesis, stress response pathways and plant immunity mechanisms. Here, we identified five PutACBP members in alkaligrass (Puccinellia tenuiflora), which were divided into four distinct classes based on a phylogenetic tree constructed from 86 ACBP genes from 12 plant species. Promoter analysis identified numerous cis-acting elements linked to abiotic stresses (e.g., light, drought, heat, and cold) and hormone responses. Expression profile analyses revealed that PutACBPs exhibit broad expression patterns across many organs and respond to salinity-alkali, cold, H₂O₂, and CdCl₂ stresses. Transient expression of five PutACBP-GFPs in tobacco (Nicotiana tabacum) revealed PutACBP1 and PutACBP2 localized to the plasma membrane, cytoplasm, and cell nucleus, while PutACBP3, PutACBP4, and PutACBP5 localized around the plasma membrane and cytoplasm. Furthermore, heterologous constitutive expression of PutACBP3 in Arabidopsis (Arabidopsis thaliana) enhanced the resistance of transgenic plants to salinity stress, possibly through alterations in the levels of lipid metabolism-related and stress-responsive genes. The ACBP gene family is highly conserved across different plant species. This study provides the first comprehensive genomic and functional characterization of the PutACBP family in alkaligrass, elucidating its evolutionary conservation, phylogenetic classification, and stress-response roles. Notably, overexpression of PutACBP3 in Arabidopsis significantly enhanced salt tolerance, suggesting its critical function in salt-stress adaptation in alkaligrass.

Puccinellia tenuiflora is a perennial halophytic grass commonly regarded as a pioneer species for the ecological restoration of saline–alkali land. Its adaptive capacity and subsequent utilization value are shaped by interacting structural, physiological, molecular, ecological, and management-related factors. This review summarizes recent studies on saline–alkali tolerance in P. tenuiflora, with emphasis on root structural barriers, Na⁺/K⁺ homeostasis, osmotic adjustment, organic-acid metabolism, antioxidant defense, ion transport, and multi-omics regulation. To better understand the integrated stress response, we propose a functional framework that distinguishes first-line defenses from downstream cellular repair mechanisms. First-line defenses include root apoplastic barriers (Casparian strips and suberization) that restrict Na⁺ entry, plasma-membrane Na⁺/H⁺ antiporters (e.g., SOS1) that mediate active Na⁺ exclusion, and K⁺-retention mechanisms (e.g., AKT1, HKT2;1) that preserve cytosolic K⁺/Na⁺ homeostasis—these operate rapidly to prevent ion imbalance at the onset of stress. Downstream repair and acclimation mechanisms include osmotic adjustment via compatible solutes (e.g., proline, glycine betaine), organic-acid accumulation (especially citric acid) for pH regulation and chelation, ROS scavenging systems, and proteomic/phosphoproteomic reprogramming that repair stress-induced damage and restore metabolic balance. Furthermore, saline–alkali stress involves both short-term osmotic shock and long-term ionic toxicity, and available evidence suggests a temporal shift in the relative importance of these mechanisms: osmotic adjustment and rapid ion exclusion dominate during the initial hours to days of stress, whereas organic-acid metabolism, ROS buffering, and molecular reprogramming become increasingly important during prolonged exposure, sustaining tissue integrity and enabling long-term persistence. Current evidence indicates that saline–alkali tolerance in P. tenuiflora results from the combined action of several processes, including restricted Na⁺ entry, K⁺ retention, organic-acid accumulation, reactive oxygen species homeostasis, and organ-specific molecular responses. This review also discusses the significance of P. tenuiflora in community establishment, saline–alkali land restoration, and post-restoration forage utilization. Field studies and limited feeding trials suggest that P. tenuiflora can provide biomass and utilization potential after community stabilization. However, based on current evidence, it is more appropriate to define its forage value as a post-restoration utilization extension rather than as that of a fully developed specialized forage crop. Further studies are required on nutritional quality, mineral-element safety, long-term field management, and animal feeding validation.