Cadmium (Cd) pollution in soil poses a global concern due to its serious impacts on human health and ecological security. In plants, tremendous efforts have been made to identify some key genes and pathways in Cd stress responses. However, studies on the roles of epigenetic factors in response to Cd stress were still limited. In the study, we first gain insight into the gene expression dynamics for maize seedlings under 0 h, 12 h, and 72 h Cd stress. As a result, six distinct groups of genes were identified by hierarchical clustering and principal component analysis. The key pathways associated with 12 h Cd stress were protein modifications including protein ubiquitination, signal transduction by protein phosphorylation, and histone modification. Whereas, under 72 h stress, main pathways were involved in biological processes including phenylalanine metabolism, response to oxygen-containing compounds and metal ions. Then to be noted, one of the most highly expressed genes at 12 h under Cd treatment is annotated as histone demethylases (). The evolutionary tree analysis and domain analysis showed that belonged to the JmjC-only subfamily of the Jumonji-C (JmjC) family, and was conserved in rice and Arabidopsis. After 72 h of Cd treatment, the mutant created by EMS treatment manifested less severe chlorosis/leaf yellowing symptoms compared with wild-type plants, and there was no significant difference in Fv/Fm and φPSII value before and after Cd treatment. Moreover, the expression levels of several photosynthesis-related down-regulated genes in EMS mutant plants were dramatically increased compared with those in wild-type plants at 12 h under Cd treatment. Our results suggested that plays an important role in the Cd tolerance response pathway and will facilitate the development of cultivars with improved Cd stress tolerance.

中文翻译：

---

动态转录组分析揭示了玉米中与镉胁迫相关的关键基因 ZmJMJ20 和途径

土壤镉（Cd）污染严重影响人类健康和生态安全，引起全球关注。在植物中，人们付出了巨大的努力来确定镉胁迫反应中的一些关键基因和途径。然而，关于表观遗传因素在镉胁迫响应中的作用的研究仍然有限。在这项研究中，我们首先深入了解了玉米幼苗在 0 小时、12 小时和 72 小时镉胁迫下的基因表达动态。结果，通过层次聚类和主成分分析鉴定了六组不同的基因。与 12 小时镉胁迫相关的关键途径是蛋白质修饰，包括蛋白质泛素化、蛋白质磷酸化信号转导和组蛋白修饰。而在72小时应激下，主要通路涉及苯丙氨酸代谢、对含氧化合物和金属离子的反应等生物过程。然后值得注意的是，Cd 处理 12 小时时表达最高的基因之一被注释为组蛋白去甲基酶 ()。进化树分析和结构域分析表明，该基因属于Jumonji-C（JmjC）家族中仅存在JmjC的亚科，在水稻和拟南芥中保守。 Cd处理72 h后，与野生型相比，EMS处理产生的突变体表现出较轻的失绿/叶片黄化症状，且Cd处理前后Fv/Fm和φPSII值无显着差异。此外，在Cd处理12 h时，与野生型植物相比，EMS突变体植物中多个光合作用相关下调基因的表达水平显着增加。我们的结果表明，它在镉耐受反应途径中发挥着重要作用，并将促进具有改善的镉胁迫耐受性的品种的开发。