In silico characterization of C3H transcription factors reveals key regulators of fungal disease responses in apple (Malus domestica)

Apple ( Malus domestica ) is a widely cultivated fruit tree crop with genetic and phenotypic diversity and bioactive compounds that have been valued for health-promoting aspects. Although it is an important fruit crop, transcription factor regulation for signaling pathways related to biotic stress tolerance has not been fully characterized. C3H transcription factor family is one of the most important families of transcription factors which is actively involved in plant development and stress responses. It has been studied across plant species, but its role in apple responses to biotic stress remains poorly characterized. In this study, 60 C3Hs were identified and named from MdC3H01 to MdC3H60 according to their distribution on all 17 chromosomes. These genes were then distributed into different groups based on their homology with Arabidopsis thaliana , Prunus persica and Oryza sativa . The synteny analysis was performed with two other species to explore evolutionary relationships among them. Twenty-three segmentally duplicated gene pairs and two tandemly duplicated gene pairs were identified in collinearity analysis. Gene expression analysis revealed that MdC3H16 , MdC3H37 were highly induced in response to Venturia inaequalis , Gymnosporangium yamadae , and Alternaria alternata . These genes act as central regulators in coordinating defense responses against multiple pathogens. In this study, the roles of C3H s were studied extensively in plant development and against fungal pathogens. These findings offer valuable genetic resources for developing stress-resilient cultivars with improved resistance to biotic stress through molecular breeding.