Structural determinants of miR156a precursor processing in temperature-responsive flowering in Arabidopsis.
Structural determinants of miR156a precursor processing in temperature-responsive flowering in Arabidopsis.
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DOI：
10.1093/jxb/erw248
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发表时间：
2016-08
影响因子：
6.9
通讯作者：
Ahn JH
中科院分区：
文献类型：
--
作者：
Kim W;Kim HE;Jun AR;Jung MG;Jin S;Lee JH;Ahn JH
在Arabdiposis中，pri-miR 156 a的上部茎对于miR 156 a生物发生是重要的，与第一切割位点相邻的第二茎在调节环境温度响应性开花中起作用。microRNA起源于含有发夹结构的初级转录物（pri-miRNAs）。植物pri-miRNAs具有高度可变的结构，并且对其二级结构中编码的信息知之甚少。拟南芥miR 156是一种环境温度响应型miRNA，在植物开花时间调控中起重要作用。为了确定miR 156加工的结构决定因素，我们分析了在pri-miR 156 a的上部茎中引入的突变对其温度依赖性加工和开花时间的影响。在不同温度下，pri-miR 156 a和成熟miR 156的表达水平相反。与未突变的构建体相比，上部茎中的突变，特别是更接近miR 156 a/miR 156 a * 双链体的区域，减少了23 °C和16 °C下的miR 156加工，并导致不太严重的表型。pri-miR 156 a的第一切割位点附近的第二茎中的突变在23 °C下影响miR 156的加工，但在16 °C下不影响。这也见于pri-miR 172 a，另一种环境温度响应性miRNA。pri-miR 172 a的上部茎替换pri-miR 156 a的上部茎严重影响miR 156的加工和开花时间。这些结果表明，pri-miR 156 a的上部茎对于miR 156在不同温度下的加工是重要的。特别地，邻近第一切割位点的第二茎在调节环境温度响应性开花中起作用。
In Arabdiposis, the upper stem of pri-miR156a is important for miR156a biogenesis, with the second stem adjacent to the first cleavage site playing a role in regulating ambient temperature-responsive flowering. MicroRNAs originate from primary transcripts (pri-miRNAs) containing hairpin structures. Plant pri-miRNAs have highly variable structures and little is known about the information encoded in their secondary structures. Arabidopsis miR156 is an ambient temperature-responsive miRNA and plays an important role in regulating flowering time. To identify the structural determinants for miR156 processing, we analyzed the effects of mutations introduced in the upper stem of pri-miR156a on its temperature-dependent processing and flowering time. The levels of pri-miR156a and mature miR156 were opposite at different temperatures. Mutations in the upper stem, especially the region closer to the miR156a/miR156a* duplex, reduced miR156 processing at 23 °C and 16 °C and caused a less severe phenotype compared with the un-mutated construct. Mutation in the second stem near the first cleavage site of pri-miR156a affected miR156 processing at 23 °C, but not at 16 °C. This was also seen in pri-miR172a, another ambient temperature-responsive miRNA. Replacement of the upper stem of pri-miR156a with that of pri-miR172a severely affected miR156 processing and flowering time. These results suggested that the upper stem of pri-miR156a is important for miR156 processing at different temperatures. In particular, the second stem adjacent to the first cleavage site plays a role in the regulation of ambient temperature-responsive flowering.