Molecular characterization and expression analysis of DNA methyltransferase genes during kiwifruit ripening

Abstract DNA methylation plays an important role in plant growth and development, fruit ripening and stress response. DNA methylation is catalyzed by DNA methyltransferase (DNMT). DNMT genes have been isolated and identified from Arabidopsis, rice, tomato, peanut and other plants, but it has not been reported in kiwifruit. In this study, 16 DNMTs were screened and identified from kiwifruit, named AcDMT1-AcDMT16 and mainly distributed in 12 chromosomes. By predicting the subcellular localization of DNMT in kiwifruit, it was found that most of DNMT were enzyme proteins located in the nucleus. Phylogenetic tree analysis showed that among the 16 kiwifruit DNMTs, 4 members belonged to the MET subfamily, 7 belonged to the CMT, and 5 belonged to the DRM, in addition, kiwifruit was closely related to tomato. Protein structure analysis showed that there were great differences in the structure of kiwifruit DNMT, most of which did not have transmembrane structure, and the domains of each subfamily were relatively conservative. qRT-PCR and correlation analysis results showed that AcDMT3, AcDMT6 and AcDMT7 were increased with the continuous fruit ripening and softening, indicating they positively regulate kiwifruit ripening, but AcDMT1, AcDMT9, AcDMT10, AcDMT12 and AcDMT13 were reverse. The results provide basic information for functional analysis and further study of DNMTs in kiwifruit.