Genome-Wide Characterization, Expression, and Functional Analysis of Acyl-CoA-Binding Protein (ACBP) Gene Family in Puccinellia tenuiflora

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 <i>PutACBP</i> members in alkaligrass (<i>Puccinellia tenuiflora</i>), which were divided into four distinct classes based on a phylogenetic tree constructed from 86 <i>ACBP</i> genes from 12 plant species. Promoter analysis identified numerous <i>cis</i>-acting elements linked to abiotic stresses (e.g., light, drought, heat, and cold) and hormone responses. Expression profile analyses revealed that <i>PutACBPs</i> 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 (<i>Nicotiana tabacum</i>) 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 <i>PutACBP3</i> in <i>Arabidopsis</i> (<i>Arabidopsis thaliana</i>) enhanced the resistance of transgenic plants to salinity stress, possibly through alterations in the levels of lipid metabolism-related and stress-responsive genes. The <i>ACBP</i> 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 <i>PutACBP3</i> in <i>Arabidopsis</i> significantly enhanced salt tolerance, suggesting its critical function in salt-stress adaptation in alkaligrass.