Light-Inducible MiR163 Targets PXMT1 Transcripts to Promote Seed Germination and Primary Root Elongation in Arabidopsis
Light-Inducible MiR163 Targets PXMT1 Transcripts to Promote Seed Germination and Primary Root Elongation in Arabidopsis
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DOI：
10.1104/pp.15.01188
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发表时间：
2016-03-01
期刊：
影响因子：
7.4
通讯作者：
Chua, Nam-Hai
中科院分区：
文献类型：
--
作者：
Chung, Pil Joong;Park, Bong Soo;Chua, Nam-Hai
许多植物microRNA的表达对激素和环境刺激有反应，但没有一个与光有关。拟南芥（Arabidopsis thaliana）miR 163长24个核苷酸，靶向编码几种S-腺苷-蛋氨酸依赖性羧基甲基转移酶家族成员的mRNA。在这里，我们发现miR 163在幼苗脱黄化以及种子萌发期间被光高度诱导。在相同的条件下，其目标PXMT 1，编码甲基转移酶，甲基化1，7-副黄嘌呤，下调。在mir 163无效突变体中，PXMT 1的光阻遏被消除，但在mir 163突变体背景中表达pri-miR 163基因的互补系中，阻遏可以恢复到野生型水平。在种子萌发过程中，miR 163及其靶基因PXMT 1主要在胚根中表达，并且这两个基因的表达模式呈负相关。此外，与野生型相比，mir 163突变体或PXMT 1过表达系在连续光照下表现出延迟的种子萌发，并且幼苗在长日照条件下发育较短的初生根和增加的侧根数量。总之，我们的研究结果表明，miR 163靶向PXMT 1 mRNA，以促进种子萌发和调节拟南芥幼苗早期发育过程中的根结构。
Expression of many plant microRNAs is responsive to hormones and environmental stimuli, but none has yet been associated with light. Arabidopsis (Arabidopsis thaliana) miR163 is 24 nucleotides in length and targets mRNAs encoding several S-adenosyl-Metdependent carboxyl methyltransferase family members. Here, we found that miR163 is highly induced by light during seedling deetiolation as well as seed germination. Under the same condition, its target PXMT1, encoding a methyltransferase that methylates 1,7-paraxanthine, is down-regulated. Light repression of PXMT1 is abolished in a mir163 null mutant, but the repression can be restored to wild-type levels in complementation lines expressing pri-miR163 gene in the mir163 mutant background. During seed germination, miR163 and its target PXMT1 are predominantly expressed in the radicle, and the expression patterns of the two genes are inversely correlated. Moreover, compared with the wild type, mir163 mutant or PXMT1 overexpression line shows delayed seed germination under continuous light, and seedlings develop shorter primary roots with an increased number of lateral roots under long-day condition. Together, our results indicate that miR163 targets PXMT1 mRNA to promote seed germination and modulate root architecture during early development of Arabidopsis seedlings.