Identification And Preliminary Research On The Function Of 6mA Methyltransferase In Arabidopsis Thaliana

6mA is widely distributed in the Arabidopsis thaliana genome and is closely related to actively expressed genes.The dynamics of 6mA modifications depends on the 6mA regulatory proteins.In plants,there are few reports on 6mA modification and its regulatory proteins.DAMT-1,which is homolog of the MT-A70 family proteins,is a6 m A methyltransferase in C.elegans.DAMT-1 is highly conserved in eukaryotes.AtDAMT1 is a homolog of DAMT-1 in Arabidopsis thaliana.In this study,we hypothesized that AtDAMT1 is involved in the regulation of DNA 6mA methylation in Arabidopsis thaliana.We found that loss of function mutants of AtDAMT1 were sensitive to heat stress,suggesting AtDAMT1 is involved in plant heat stress response.We used WT(Col-0),atdamt1 mutant,ATDAMT1 complementation(com)lines and overexpression(OE)lines to study the biological functions of ATDAMT1.The following conclusion has been drawn from this study:1.AtDAMT1 is a homolog of DAMT-1 in Arabidopsis thaliana.2.Two loss of function mutants atdamt1-1 and atdamt1-2 were obtained.Both mutants showed reduced 6mA levels compared to WT.3.AtDAMT1 could add methylation on plant genomic DNA in vitro.4.AtDAMT1 is a nuclear-localized protein.atdamt1-1 mutant showed reduced tolerance of heat stress.In response to heat stress,the 6mA signal of WT and atdamt1 mutant were significantly enhanced.Overexpression of the AtDAMT1 enhanced the thermotolerance.5.RNA-seq analysis showed up-regulation of expression of genes involved in heat stress response,photosynthesis,PS I light energy capture,pigment binding and chlorophyll binding in response to heat stress were higher in WT than atdamt1-1.Thus,AtDAMT1 might participate in heat stress response by regulating these signaling pathways.These results laid a foundation for studying the relationship between 6mA modification and heat stress in Arabidopsis thaliana.We will further illuminate the molecular mechanism of regulation of heat stress adaption by 6mA.