Indirect somatic embryogenesis (ISE) establishment for Coffea species started in the 1970s. Since then, intraspecific variations in the morphogenic pathway have been reported, even in the common environmental condition in vitro. Several authors have suggested that these variations are the result of genetic, epigenetic, and/or physiological events, highlighting the need for investigations to know the causes. Along these lines, this study aimed to investigate and describe, for the first time, the global 5-methylcytosine and physiological changes that occur in the cells of the aggregate suspensions of Coffea canephora during proliferation and somatic embryo regeneration steps. The cell proliferation step was characterized by increase in cell mass in all subcultures; relatively low mean values of global 5-methylcytosine (5-mC%), abscisic acid (ABA), and indole-3-acetic acid (IAA); high mean value of 1-aminocyclopropane-1-carboxylic acid (ACC, an ethylene precursor); and increase followed by decrease in spermidine (Spd, a polyamine) level. Therefore, these epigenetic and physiologic aspects promoted the cell proliferation, which is fundamental for ISE. In turn, the somatic embryo regeneration was correlated with global 5-mC% and physiological changes. The competence acquisition, determination, and cell differentiation steps were marked by increases in mean values of 5-mC%, IAA and ABA, and decreases in ACC and Spd, evincing that these changes are the triggers for regeneration and maturation of somatic embryos. Therefore, dynamic and coordinated epigenetic and physiologic changes occur in the cells of the aggregate suspensions during the C. canephora ISE in liquid system.

中文翻译：

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全球 5-甲基胞嘧啶和生理变化是 Coffea canephora 间接体细胞胚胎发生的触发因素

咖啡属的间接体细胞胚胎发生 (ISE) 建立始于 1970 年代。从那时起，即使在体外的常见环境条件下，也报道了形态发生途径的种内变异。几位作者提出这些变异是遗传、表观遗传和/或生理事件的结果，强调需要进行调查以了解原因。沿着这些思路，本研究旨在首次调查和描述在增殖和体细胞胚胎再生步骤中，咖啡豆聚合悬浮液的细胞中发生的全局 5-甲基胞嘧啶和生理变化。细胞增殖步骤的特征在于所有继代培养物中细胞质量的增加；全球 5-甲基胞嘧啶 (5-mC%)、脱落酸 (ABA) 的平均值相对较低，和吲哚-3-乙酸（IAA）；1-氨基环丙烷-1-羧酸（ACC，乙烯前体）的高平均值；和亚精胺（Spd，一种多胺）水平随后增加。因此，这些表观遗传和生理方面促进了细胞增殖，这是 ISE 的基础。反过来，体细胞胚胎再生与全局 5-mC% 和生理变化相关。能力获得、确定和细胞分化步骤的特点是 5-mC%、IAA 和 ABA 的平均值增加，以及 ACC 和 Spd 的减少，表明这些变化是体细胞胚胎再生和成熟的触发因素。因此，在液体系统中的 C. canephora ISE 期间，聚合悬浮液的细胞中发生动态和协调的表观遗传和生理变化。