Genomic Methylated Cytosine Level during the Dedifferentiation and Cellular Competence in Coffea arabica Lines: Insights about the Different In Vitro Responses

Abstract

Coffea arabica genotypes present distinct responses in vitro, and somaclonal variation occurrence has been reported. Global cytosine methylation is one of the epigenetic mechanisms that influences the Coffea in vitro responses. We aimed to establish the indirect somatic embryogenesis in C. arabica ‘Catuaí Vermelho’, ‘Caturra’ and ‘Oeiras’, associate the distinct responses to the methylated cytosine genomic level, and check the ploidy stability. Leaf explants were cultured in callus induction and proliferation medium. The resulted calli were transferred to the regeneration medium, and the mature cotyledonary somatic embryos were transferred to the seedling medium. ‘Oeiras’ exhibited the highest number of responsive leaf explants, followed by ‘Caturra’ and ‘Catuaí Vermelho’. Global methylated cytosine level increased over time in the ‘Catuaí Vermelho’ and ‘Caturra’ friable calli, remaining constant in ‘Oeiras’. ‘Oeiras’ did not regenerate somatic embryos, while ‘Catuaí Vermelho’ exhibited the highest number. Somatic embryo regeneration was associated with the increase of the methylated cytosine level. However, the ‘Catuaí Vermelho’ embryogenic calli showed a lower methylated cytosine level than ‘Caturra’. Recovered plantlets exhibited the same 2C value and chromosome number to the explant donors. Therefore, cytosine hypermethylation occurred during C. arabica indirect somatic embryogenesis, influencing cell competence and somatic embryos regeneration.