FRIGIDA-like gene family in rapeseed: genome-wide analysis and expression analysis to exogenous phytohormones.

Frigida (FRI) plays diverse roles in regulating plant flowering and drought tolerance. The biological importance of FRIGIDA-like proteins (FRL) has been well established in Arabidopsis and soybean; however, systemic analysis of the FRL gene in rapeseed in response to phytohormones is still in its infancy. The present study predicted 28 FRL proteins in rapeseed that were unevenly distributed across the entire chromosome set of rapeseeds. Phylogenetically, all BnaFRL proteins were clustered into four distinct clades along with Arabidopsis, rice, and soybean. Our study indicated that rapeseed BnaFRL arose from segmental duplication alongside single tandem duplication events. Moreover, gene structure analysis, such as Frigida domain presence, intron-exon distribution, and conserved domain analysis, validated the phylogenetic conservation of all the BnaFRL genes. Additionally, promoter analysis revealed several cis-regulatory elements related to hormones, suggesting their significant role in rapeseed hormone response mechanisms. Spatial expression across different tissues exhibited variable expression, whereas subcellular localization and temporal expression of selected BnaFRLs to exogenous hormone application (IAA, ABA, and GA) further supported their role in hormone responsiveness in rapeseed. In summary, our comprehensive analysis offers valuable insights into the evolution and potential functions of BnaFRL genes, emphasizing their significance in phytohormone responses, and establishing a foundation for further research on the BnaFRL family.