Systematic Survey and Expression Analysis of the Glutaredoxin Gene Family in Capsicum annuum Under Hypoxia Stress

Glutaredoxins (GRXs) are important proteins in plant development and environmental adaptation. Despite extensive characterization of <i>GRX</i> gene family members in various plant species, limited research has been conducted on the identification and functional analysis of <i>GRXs</i> in the economically important Solanaceae family pepper (<i>Capsicum annuum</i>). This study identified 35 typical <i>GRX</i> genes in pepper and categorized them into three distinct groups: CC-, CGFS-, and CPYC-type, based on the phylogenetic topology, which was consistent with motif or domain arrangement, and gene structures. Furthermore, the determination of ω values indicated that purifying selection was a significant factor in the evolutionary diversification of <i>GRX</i> genes in the eudicot family. Intra-genome investigations demonstrated that both segmental and tandem duplications were involved in the expansion of <i>CaGRX</i> genes. Moreover, examination of collinearity within the Solanaceae family revealed 53 orthologous pairs of <i>GRX</i> genes. Additionally, prediction of <i>cis</i>-regulatory elements and analysis of expression profiles revealed the significant involvement of <i>GRX</i> genes in plant stress response, specifically in relation to hypoxia and submergence. Subsequent subcellular localization examination suggested <i>CaGRX</i> may be involved in the endomembrane system and regulation of oxidative balance in plants. Collectively, these findings enhance our comprehension of the structural and functional properties of <i>GRX</i> in pepper, and establish a groundwork for subsequent functional characterization of the <i>CaGRX</i> genes.