The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, School of Life Sciences, Shandong University, Jinan, Shandong, China.
Plant Cell Physiol. 2017 Oct 1;58(10):1789-1800. doi: 10.1093/pcp/pcx117.
Many plant cells retain their totipotency when cultured in vitro. The regulation of shoot regeneration from in vitro culture involves a number of gene products, but the nature of the associated post-transcriptional events remains largely unknown. Here, the post-transcriptional regulator ARGONAUTE10 (AGO10), a protein which is specifically expressed in the explant during the period when pro-shoot apical meristems (SAMs) are forming, has been known to inhibit shoot regeneration. In in vitro cultured explants of the loss-of-function mutant ago10, a much larger than normal number of SAMs was formed and, in these, the stem cell marker genes WUSCHEL, CLAVATA3 and SHOOT MERISTEMLESS were all strongly expressed. AGO10 repressed the accumulation of the microRNAs miR165/166, thereby up-regulating a suite of HD-ZIP III genes. The overproduction of miR166 was shown to promote shoot regeneration, while the absence of miR165/166 message resulted in a blockage to shoot regeneration and only a partial rescue of the phenotype of the ago10 mutant. The major conclusion was that the shoot regeneration inhibition determined by AGO10 functions via the repression of miR165/166.
许多植物细胞在体外培养时保留其全能性。体外培养中茎再生的调控涉及许多基因产物，但相关的转录后事件的性质在很大程度上仍是未知的。在这里，已知转录后调节因子 ARGONAUTE10（AGO10）是一种在原茎尖分生组织（SAM）形成期间在外植体中特异性表达的蛋白质，它抑制茎再生。在功能丧失突变体 ago10 的体外培养外植体中，形成了比正常数量多得多的 SAM，并且在这些 SAM 中，干细胞标记基因 WUSCHEL、CLAVATA3 和 SHOOT MERISTEMLESS 均强烈表达。AGO10 抑制了 microRNA miR165/166 的积累，从而上调了一套 HD-ZIP III 基因。miR166 的过度产生被证明可以促进茎再生，而 miR165/166 缺失则导致茎再生受阻，仅能部分挽救 ago10 突变体的表型。主要结论是，由 AGO10 决定的茎再生抑制作用通过抑制 miR165/166 起作用。
