Vernalization-responsive intronless genes in faba bean and the development of KASP markers

The vernalization-responsive intronless gene in faba bean, VfERF017, functions as a flowering repressor, and its KASP marker enables early flowering selection with 83.15% accuracy. In this study, the genomic characteristics of intronless genes in faba bean (Vicia faba L.) and their changes in expression during vernalization-regulated flowering were systematically analyzed by bioinformatics analysis and transcriptome sequencing. A comparative analysis between the vernalization-sensitive cultivar Yundou 1183 and the insensitive cultivar Haiqing No. 1 revealed 888 intronless differentially expressed genes (DEGs), of which 58 were common to both varieties. Two key genes, VfERF017 and VfH2B, were screened from these 58 common genes, and both were significantly downregulated by vernalization treatment, which was confirmed by quantitative real-time PCR (qRT-PCR). VfERF017 belongs to the Apetala2/ethylene responsive factor (AP2/ERF) transcription factor family; its overexpression in Arabidopsis thaliana resulted in increased rosette leaf number and delayed flowering, demonstrating its function as a flowering repressor. A dual-luciferase complementation assay confirmed the direct interaction between VfERF017 and VfCBF4, coupling vernalization signaling with flowering regulation. A kompetitive allele-specific PCR (KASP) marker based on VfERF017 achieved 83.15% accuracy across 89 accessions, with the CC genotype flowering significantly earlier than the TT genotype. These findings reveal the roles of intronless genes in the vernalization response and provide a molecular tool for breeding early flowering varieties.