A gain-of-function Bushy dwarf tiller 1 mutation in rice microRNA gene miR156d caused by insertion of the DNA transposon nDart1.
A gain-of-function Bushy dwarf tiller 1 mutation in rice microRNA gene miR156d caused by insertion of the DNA transposon nDart1.
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DOI：
10.1038/srep14357
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发表时间：
2015-09-25
影响因子：
4.6
通讯作者：
Tsugane K
中科院分区：
文献类型：
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作者：
Hayashi-Tsugane M;Maekawa M;Tsugane K
水稻中的一个非自主DNA转座子nDart1在自然条件下被一个自主元件aDart1主动转座。利用内源nDart1/aDart1系统构建了nDart1启动子基因标签系，有效地获得了各种水稻突变体。虽然显性突变偶尔会从标记系中分离出来，但目前还不清楚是什么导致了显性突变。从该标记系中获得了一个半显性突变体丛生矮秆分蘖1号(Bdt1)，该突变体具有多分蘖和矮化的农艺性状。Bdt1突变体在非蛋白编码基因miR156d转录起始点上游38个碱基上新插入了一个nDart1。这一插入导致miR156d转录起始点上游移位，从而增加了产生成熟microRNAs的功能转录本。这些结果表明，miR156d的总量不仅受转录本数量的控制，还受转录本质量的控制。此外，转基因株系在5‘端的nDart1序列两侧引入了miR156d片段，表明在基因启动子区域插入nDart1增强了基因作为顺式元件的表达。这项研究证明了nDart1产生功能增益突变的能力，以及对转座元件在基因组进化中的功能的进一步见解。
A non-autonomous DNA transposon in rice, nDart1, is actively transposed in the presence of an autonomous element, aDart1, under natural conditions. The nDart1-promoted gene tagging line was developed using the endogenous nDart1/aDart1 system to generate various rice mutants effectively. While the dominant mutants were occasionally isolated from the tagging line, it was unclear what causes dominant mutations. A semidominant mutant, Bushy dwarf tiller1 (Bdt1), which has the valuable agronomic traits of multiple tillering and dwarfism, was obtained from the tagging line. Bdt1 mutant carried a newly inserted nDart1 at 38-bp upstream of transcription initiation site of a non-protein-coding gene, miR156d. This insertion caused an upstream shift of the miR156d transcription initiation site and, consequently, increased the functional transcripts producing mature microRNAs. These results indicate that the total amount of miR156d is controlled not only by transcript quantity but also by transcript quality. Furthermore, transgenic lines introduced an miR156d fragment that flanked the nDart1 sequence at the 5′ region, suggesting that insertion of nDart1 in the gene promoter region enhances gene expression as a cis-element. This study demonstrates the ability of nDart1 to produce gain-of-function mutants as well as further insights into the function of transposable elements in genome evolution.