Objective To Identify Dof (DNA binding with one finger) gene family members in Mongolian Sea Buckthorn (Hippophae rhamnoides subsp. mongolica) and Explore Key Dof Genes regulating oil synthesis and accumulation in fruit flesh

Methods Bioinformatics approaches were used to identify the Dof gene family members in the sea buckthorn genome, followed by a systematic analysis of their protein domains, conserved motifs, cis-regulatory elements, and phylogenetic relationships. Absolute quantification transcriptome sequencing (Unique Molecular Identifier RNA-seq, UMI RNA-seq) was performed on the fruit flesh of 12 sea buckthorn germplasm lines. Key candidate Dof genes were identified based on the expression levels of Dof family members and the oil content in the fruit flesh.

Results A total of 47 Dof members were identified in the sea buckthorn genome, unevenly distributed across 12 chromosomes. Ten motifs were identified, with cis-regulatory elements related to plant oil synthesis and development. The Dof gene family was classified into three subfamilies, and phylogenetic analysis revealed that some sea buckthorn Dofs were closely related to the Dofs regulating oil synthesis in soybean (NP001236530.2, NP001315363.1). UMI RNA-seq analysis of the fruit flesh during different developmental stages of the sea buckthorn germplasms showed that the expression of HrDof1.2 (Hic_asm_12.312 8) gene during the orange fruit stage was significantly higher than in the green fruit stage, and was closely correlated with the variation in oil content in the corresponding germplasms.

Conclusion Members of the sea buckthorn Dof gene family are involved in oil synthesis and development. The expression of the HrDof1.2 gene is closely related to the oil content in the fruit flesh, providing a scientific basis for further elucidation of the regulatory mechanism of oil synthesis and accumulation by Dof genes in sea buckthorn.