DICER-LIKE3 Activity in Physcomitrella patens DICER-LIKE4 Mutants Causes Severe Developmental Dysfunction and Sterility
DICER-LIKE3 Activity in Physcomitrella patens DICER-LIKE4 Mutants Causes Severe Developmental Dysfunction and Sterility
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DOI：
10.1093/mp/sss036
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发表时间：
2012-11-01
期刊：
影响因子：
27.5
通讯作者：
Frank, Wolfgang
中科院分区：
文献类型：
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作者：
Arif, M. Asif;Fattash, Isam;Frank, Wolfgang
反式作用小干扰RNA（ta-siRNA）是在microRNA依赖性切割、转化为双链RNA和Dicer依赖性分相加工后从TAS前体转录物释放的植物特异性siRNA。与微小RNA（miRNA）一样，ta-siRNA在广泛互补的位点指导靶RNA的位点特异性切割。在这里，我们表明小立碗藓的DICER-LIKE 4蛋白（PpDCL 4）对于21个核苷酸（nt）ta-siRNA的生物合成是必需的。在Delta PpDCL 4突变体中，由于PpDCL 3活性，尺寸过大的23和24-nt ta-siRNA积累。Delta PpDCL 4突变体在立碗藓属的整个发育过程中显示出严重的异常，包括不育，这在Delta PpDCL 3/Delta PpDCL 4双突变体植物中完全逆转。因此，PpDCL 3活性，而不是PpDCL 4功能本身的丧失，是Delta PpDCL 4表型的原因。此外，我们描述了几个新的立碗藓属的反式作用siRNA位点，其中三个属于一个新的家族，TAS 6。TAS 6基因座以切割的miR 156和miR 529靶位点为代表，并且与PpTAS 3基因座非常接近。
Trans-acting small interfering RNAs (ta-siRNAs) are plant-specific siRNAs released from TAS precursor transcripts after microRNA-dependent cleavage, conversion into double-stranded RNA, and Dicer-dependent phased processing. Like microRNAs (miRNAs), ta-siRNAs direct site-specific cleavage of target RNAs at sites of extensive complementarity. Here, we show that the DICER-LIKE 4 protein of Physcomitrella patens (PpDCL4) is essential for the biogenesis of 21 nucleotide (nt) ta-siRNAs. In Delta PpDCL4 mutants, off-sized 23 and 24-nt ta-siRNAs accumulated as the result of PpDCL3 activity. Delta PpDCL4 mutants display severe abnormalities throughout Physcomitrella development, including sterility, that were fully reversed in Delta PpDCL3/Delta PpDCL4 double-mutant plants. Therefore, PpDCL3 activity, not loss of PpDCL4 function per se, is the cause of the Delta PpDCL4 phenotypes. Additionally, we describe several new Physcomitrella trans-acting siRNA loci, three of which belong to a new family, TAS6. TAS6 loci are typified by sliced miR156 and miR529 target sites and are in close proximity to PpTAS3 loci.