植物细胞具有全能性,创伤和外源激素能够诱导已分化细胞的重编程来再生新的植株,发展的植物组织培养技术已广泛应用于植物快速繁殖、种质保存和性状改良等多个方面。然而,对植物组织培养过程中细胞如何保持分化状态和发育可塑性的分子调控机制仍知之甚少,尤其是在表观遗传学水平上。DNA甲基化是一种进化上保守的表观遗传修饰,能够复杂地协调植物细胞全能性建立和影响其命运转变。在此,以组织培养过程中的愈伤组织形成、体细胞胚发生为切入点,总结了DNA甲基化参与植物再生过程的最新进展。首先,分析了不同植物再生过程中全基因组DNA甲基化变化模式,认为外植体类型和再生阶段均会对DNA甲基化水平产生影响;其次,重点研究了甲基化转移酶(MET1)等在植物再生过程中的作用,以及DNA甲基化调控再生基因表达的分子机制,包括BBM(baby boom),WOX(wuschel-related homeobox),WIN(wound induced dedifferentiation)等基因,最后,讨论了DNA甲基化在植物再生领域的未来研究方向,指出组织培养与基因工程的结合将为农作物和经济、用材林木的高效繁殖和精准培育提供机遇。

Exerting remarkable cell totipotence, plants are able to regenerate tissues/organs and even individuals from differentiated cells activated by wound stress and/or hormonal cues. Based on the theory of plant cell totipotency, techniques of plant tissue culture have been widely used in rapid propagation, germplasm conservation, and plant breeding as a type of conserved epigenetic modification. However, the understanding of how plant cells retain both differentiated status and developmental plasticity is still obscure, especially at the epigenetic level. DNA methylation is an evolutionarily conserved epigenetic modification that can intricately coordinate cell fate transition and pluripotency establishment during the plant regenerate process. In the work, the recent progress in the regulation of plant regeneration through DNA methylation was summarized, starting from the formation of callus and somatic embryogenesis during tissue culture. Firstly, the change patterns of DNA methylation in different plant regeneration processes were analyzed, showing that both explants type and regeneration phase had an effect on DNA methylation levels. The role of some DNA methyltransferase in plant regeneration was studied, such as DNA Methyltransferase1 (MET1), whose deletion can lead to increased WUS expression and promote shoot regeneration. RNA-directed DNA methylation (RdDM) is the main molecular pathway responsible for de novo DNA methylation in all contexts and is believed to play an important role in plant regeneration. Meanwhile, we analyzed the molecular regulatory mechanisms of DNA methylation on the expression of regenerative genes, such as BBM (baby boom), WOX (wuschel-related homeobox), WIN (wound induced dedifferentiation), etc. Finally, we discussed the future research directions of DNA methylation in the field of plant regeneration. The combination of tissue culture and genetic engineering will provide opportunities for efficient reproduction and precise cultivation of agricultural and forestry crops. Further, the regeneration-related genes reported in this study will provide candidates for plant regeneration research of genetic and molecular mechanisms.