Plant Journal|四川农大、作物所等单位共同揭示MicroRNAs和DNA甲基化协同调控玉米胚乳淀粉合成

淀粉合成是作物灌浆的基本特征，但对其合成基因表达的分子调控机制目前仅限于转录因子(TF)。在这里，我们获得了玉米胚乳在多个发育阶段的转录组、小RNA组和DNA甲基组数据，并建立了淀粉合成的调控网络图谱。

转录组分析显示，在9-10DAP出现急剧转变，淀粉积累迅速，淀粉和蔗糖代谢上调基因丰富。表达模式分析在淀粉合成基因(SSGs)和转录因子之间建立了一个全面的网络。在玉米胚乳发育过程中，优先抑制TFs表达的miRNAs，尤其是调节SSG表达的TFs在玉米胚乳发育过程中普遍下调。

具体地说，ZmMYB138和ZmMYB115在各自的启动子区域影响Du1/Wx和AE1/BT2基因的转录活性。

值得注意的是，ZMA-miR159k-3p在转录后水平的大量表达对这两种转录因子具有负调控作用。这表明miRNAs是淀粉合成的重要调节因子。

此外，除了转录因子的情况下，SSGs和miRNAs的表达均受DNA甲基化状态的全局调控。

综上所述，本研究结果确立了miRNAs和DNA甲基化在淀粉合成中的调控功能，表明DNA甲基化是淀粉合成的主开关。

Starch synthesis is an essential feature of crop filling, but knowledge of the molecular regulatory mechanism of its synthetic genes’ expressions is currently limited to transcription factors (TFs). Here, we obtained transcriptome, small‐RNAome and DNA methylome data from maize endosperms, during multiple developmental stages and established a regulatory network atlas of starch synthesis. Transcriptome analysis showed sharp transition at 9‐10 DAP, at which starch accumulates rapidly with enrichment of up‐regulated genes of starch and sucrose metabolism. Expression pattern analysis established a comprehensive network between starch synthetic genes (SSGs) and TFs. During maize endosperm development, the miRNAs with preferential repression of the expression of TFs, particularly the TFs regulating SSG expression were extensively down‐regulated during maize endosperm development. Specifically, ZmMYB138 and ZmMYB115 affected the transcriptional activities of Du1/Wx and Ae1/Bt2 genes at their respective promoters’ regions. Remarkably, the two TFs were negatively regulated by the copious expression of Zma‐miR159k‐3p at post‐transcriptional level. This suggests that miRNAs are important regulators of starch synthesis. Moreover, with the exclusion of the TFs, the expressions of both the SSGs and miRNAs were globally regulated by DNA methylation status. Altogether, the present results established the regulatory functions of miRNAs and DNA methylation in starch synthesis, and indicated that DNA methylation was a master switch.

原文链接：

https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.15043

Hu, Y., Li, Y., Weng, J., Liu, H., Yu, G., Liu, Y., Xiao, Q., Huang, H., Wang, Y., wei, B., Cao, Y., Xie, Y., Long, T., Li, H., Zhang, J., Li, X. and Huang, Y. (2020), Coordinated regulation of starch synthesis in maize endosperm by microRNAs and DNA methylation. Plant J. Accepted Author Manuscript. doi:10.1111/tpj.15043

版权作品，未经PaperRSS书面授权，严禁转载，违者将被追究法律责任。

PaperRSS，关注生命科学，高校院所科研进展。