Genome-Wide Analysis of the APETALA2/Ethylene-Responsive Factor Gene Family in Carthamus tinctorius L

The APETALA2/ethylene-responsive factor (AP2/ERF) superfamily represents a class of transcription factors involved in plant growth, development, and stress responses. Carthamus tinctorius L., also known as safflower, is an important plant whose flowers contain carthamin, an expensive aromatic pigment with various medicinal and flavoring properties. This study aimed to elucidate the roles of these transcription factors in plant growth, metabolic regulation, and environmental adaptation in safflower, providing foundational information and theoretical support for genetic improvement and stress resilience research in this crop. In this study, we identified and characterized the AP2/ERF family genes in safflower through a comprehensive genomic analysis. A total of 127 AP2/ERF genes were identified and clustered into seven groups and 14 subgroups based on phylogenetic analysis. Multiple sequence alignment revealed that the basic region and two helical structures were highly conserved in most AP2/ERF proteins. Cis-acting elements in the promoters of the AP2/ERF genes were analyzed, and a degree of safflower specificity was observed among different safflower species. Tissue-specific expression analysis showed that 23, 21, 15, and 9 genes were most abundantly expressed in the roots, leaves, flowers, and buds, respectively, while only eight genes were highly expressed in all tissues examined. These results indicate that the AP2/ERF family genes in safflower are diverse and complex, with distinct expression patterns for different genes in different safflower species. The findings provide important fundamental data for in-depth studies of the growth, development, and stress response mechanisms in safflower.