Genome-Wide Identification and Expression Analysis of the SUC Gene Family in Peanut (Arachis hypogaea L.) Reveals Its Role in Seed Sucrose Accumulation

Sucrose is a key quality trait in peanuts, yet high-sucrose varieties are scarce. Although sucrose transporters (SUT/SUC) play crucial roles in sucrose transport and accumulation during seed development, systematic analyses in peanuts are limited. This study conducted a genome-wide analysis of the <i>SUC</i> gene family in cultivated peanut (<i>Arachis hypogaea</i> L.). Sixteen <i>AhSUC</i> genes were identified and characterized for genomic distribution, phylogeny, and expression across tissues and developmental stages. The genes are unevenly distributed across the genome with clustered chromosomal localization. All AhSUC proteins contain the conserved sucrose/proton co-transporter domain (IPR005989), exhibit the typical 12 transmembrane α-helical structure of the major facilitator superfamily, are hydrophobic, and predicted to localize to the membrane. Promoter analysis revealed cis-regulatory elements associated with growth, development, light, hormone, and stress responses. Expression profiling showed tissue-specific patterns, with eight <i>AhSUC</i> genes being highly expressed in cotyledons and embryos. Comparative analysis between high-sugar and conventional varieties showed higher expression of <i>AhSUC2</i>, <i>AhSUC9</i>, and <i>AhSUC11</i> in the high-sugar variety, correlating with increased sucrose accumulation. Functional validation using a sucrose transport-deficient yeast mutant confirmed the sucrose transport activity of these genes. These findings provide insight into sucrose accumulation mechanisms and offer genetic targets for breeding high-sugar peanut varieties.