Análise comparativa e expressão dos genes da família Dof em Citrus sinensis (L.) Osbeck durante o desenvolvimento dos frutos

Abstract

The DOF family proteins (DNA binding with One Finger) comprises unique plant transcription factors (FTs) characterized by the presence of a DNA binding domain Dof containing a similar structure to the "zinc-finger" domain. These transcription factors are involved in different roles in various biological processes in plants. Although the analysis and genomic characterization of this gene family was performed in many plant species, information on Dof genes in sweet orange (Citrus sinensis (L.) Osbeck) and their involvement in the development of the fruits is still limited. For the full identification of CsDof genes in C. sinensis, including the structures of genes, chromosomal locations, introns and phylogeny, the examination of three databases resulted in the identification of 24 genes of this FT family distributed on 7 out of 9 chromosomes of this species. Phylogenetic analysis and classification of Dof transcription factors in C. sinensis was compared with their orthologs of Arabidopsis (Arabidopsis thaliana L.) and rice (Oryza sativa L.), which allowed their classification in four major groups (A, B, C and D) and 9 subgroups (a, B1, B2, C1, C2.1, C2.2, C3, D1, D2) of DOF proteins. For gene expression analysis, the 12 Dof genes with higher abundance of transcripts in fruits based on public RNA-seq data were selected for further analysis by semi-quantitative RT-PCR. This analysis revealed the CsDof genes were differentially expressed at different stages of development (up to 90 days after anthesis). It was also possible to establish three groups regarding their transcriptional activity relative to that in leaf tissue: genes with high (up to 8X), intermediate (up to 3X) and low relative expression (below 3 X). The gene CsDof1 showed higher expression in all of the fruit development stages, indicating that this isoform plays an important role in regulating the development of the fruits of C. sinensis. Taken together, our results provide new information about the regulation of Dof genes in controlling the formation of fruits of this important fruit species.