Comprehensive genome-wide identification and expression profiling of ADF gene family in Citrus sinensis, induced by endophytic colonization of Beauveria bassiana

Endophytic entomopathogenic species are known to systematically colonize host plants and form symbiotic associations that benefit the plants they live with. The actin-depolymerizing factors (ADFs) are a group of gene family that regulate growth, development, and defense-related functions in plants. Systematic studies of ADF family at the genome-wide level and their expression in response to endophytic colonization are essential to understand its functions but are currently lacking in this field. 14ADF genes were identified and characterized in the Citrus sinensis genome. The ADF genes of C. sinensis were classified into five groups according to the phylogenetic analysis of plant ADFs. Additionally, the cis-acting analysis revealed that these genes play essential role in plant growth/development, phytohormone, and biotic and abiotic responses; and the expression analysis showed that the symbiotic interactions generate a significant expression regulation level of ADF genes in leaves, stems and roots, compared to controls; thus enhancing seedlings' growth. Additionally, the 3D structures of the ADF domain were highly conserved during evolution. These results will be helpful for further functional validation of ADFs candidate genes and provide important insights into the vegetative growth, development and stress tolerance of C. sinensis in responses to endophytic colonization by B. bassiana.