Vol.:(0123456789) 1 3 Plant Cell Reports https://doi.org/10.1007/s00299-020-02568-2 ORIGINAL ARTICLE A peak in global DNA methylation is a key step to initiate the somatic embryogenesis of coconut palm (Cocos nucifera L) Pedro Osorio‑Montalvo 1  · Clelia De‑la‑Peña 1  · Carlos Oropeza 1  · Geovanny Nic‑Can 2  · Iván Córdova‑Lara 1  · Eduardo Castillo‑Castro 1  · Luis Sáenz‑Carbonell 1 Received: 4 February 2020 / Revised: 25 June 2020 / Accepted: 10 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Key message DNA methylation, morphogenesis and gene expression during the somatic embryogenesis of Coconut are affected by 5-Azacytidine pretreatments, indicating that DNA methylation is an important factor throughout this process. Abstract Somatic embryogenesis (SE) is a process that can aid in the production of elite Cocos nucifera palms. It has been well established that epigenetic mechanisms are regulators of cell diferentiation programs; however, their role in the coconut somatic embryogenesis has not yet been addressed. To this end, the morphogenetic changes, the global DNA methylation and the expression profles of the SE-related genes and DNA methyltransferases genes were evaluated during the SE process, with and without the presence of 5-Azacytidine (AzaC). The results show that three days of pretreatments with 15 µM and 20 µM of AzaC signifcantly increased early somatic embryo formation (four- and tenfold, respectively). A clear peak of the global percentage of DNA methylation (approximately 13%) was determined at the beginning of the culture, followed by a re-establishing stage and a steady increase thereafter; in all cases, the levels of DNA methylation were lower after the pretreat- ments with AzaC. Additionally, the expression profles of the SERK, WUS, BBM and LEC genes are modulated during the SE process and the pretreatments with AzaC afect the expression profles of these genes, even at early stages. Furthermore, increased levels of expression were observed for the genes encoding for DNA methyltransferases (MET, CMT and DRM) at early and late stages of SE, indicating that DNA methylation is an important factor throughout the SE. Keywords 5-Azacytidine · In vitro tissue culture · Gene expression · Epigenetics Abbreviations AzaC 5-Azacytidine BBM BABY BOOM CMT Chromomethylase DNMTs DNA methyltransferases DRM Domains Rearranged Methyltransferase LEC1 LEAFY COTYLEDON 1 MET Methyltransferase PKL PICKLE SE Somatic embryogenesis SERK SOMATIC EMBRYOGENESIS RECEPTOR KINASE WUS WUSCHEL 2,4-D 2,4-Dichlorophenoxyacetic acid Introduction The coconut palm (Cocos nucifera L.) is a perennial and multi-purpose tree that ofers a vast variety of products with domestic and industrial applications (Arunachalam and Rajesh 2017). C. nucifera is cultivated in most tropical and subtropical countries, having a great infuence on the rural economy and on the livelihood of millions of people around the world. It is projected that the demand for coconut prod- ucts will increase exponentially in the coming years, mainly Communicated by Neal Stewart. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00299-020-02568-2) contains supplementary material, which is available to authorized users. * Luis Sáenz-Carbonell vyca@cicy.mx 1 Centro de Investigación Científca de Yucatán, Unidad de Biotecnología, Calle 43 No. 130, entre 32 y 34, Col. Chuburná de Hidalgo, 97205 Mérida, Yucatán, México 2 CONACYT-Campus de Ciencias Exactas e Ingeniería, Universidad Autónoma de Yucatán, Mérida, Yucatán, México