Genome-Wide Identification of the DOG1 Gene Family in Pepper (Capsicum annuum) and Its Expression Profiles During Seed Germination

The <i>DOG1</i> (<i>Delay of Germination1</i>) family plays key regulatory roles in seed dormancy and germination. However, a genome-wide analysis of <i>DOG1</i> genes has not been performed for pepper (<i>Capsicum annuum</i>), one of the agriculturally important species, and no studies have been conducted to characterize their expression profiles. Based on <i>C. annuum</i> genome information, the identification and expression analysis of <i>CaDOG1</i> gene family members through bioinformatics approaches can provide a theoretical foundation for subsequent studies on the biological functions of <i>CaDOG1s</i> and the improvement of seed traits in <i>C. annuum</i> breeding. In this study, a total of 13 <i>CaDOG1</i> genes were identified in the <i>C. annuum</i> genome. Phylogenetic analysis showed that these CaDOG1s, along with DOG1s from thale cress (<i>Arabidopsis thaliana</i>), rice (<i>Oryza sativa</i>), and maize (<i>Zea mays</i>), were classified into four subgroups. All <i>CaDOG1</i> genes were unevenly distributed on six <i>C. annuum</i> chromosomes, and they had relatively conserved exon-intron patterns, most with zero to one intron. According to the chromosomal distribution patterns and synteny analysis of the <i>CaDOG1</i> genes, the <i>CaDOG1</i> family expanded mainly through replication, which occurred predominantly after the divergence of dicotyledons and monocotyledons. Conserved motif analysis indicated that all encoded proteins contained Motif 2 and Motif 6, except for CaDOG1-3. Expression profile analysis using transcriptome data revealed that <i>CaDOG1</i> genes were differentially expressed across various tissues and developmental stages, with notable involvement in flowers and seeds. Quantitative real-time PCR also revealed that all <i>CaDOG1</i> genes were downregulated during seed germination, indicating that <i>CaDOG1s</i> may play negative roles in seed germination. Moreover, upon abscisic acid treatment, six <i>CaDOG1</i> genes exhibited upregulation, while in response to ethylene, four <i>CaDOG1</i> genes exhibited downregulation. Taken together, these findings provide an extensive description of the <i>C. annuum DOG1</i> gene family and might facilitate further studies for elucidating their functions in seed germination.