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Nature∣寄生植物菟丝子miRNA调节宿主植物靶mRNA的机制研究

已有 798 次阅读 2018-1-7 21:51 |系统分类:论文交流

2018年1月3日,Nature在线发表了题为“MicroRNAs from the parasitic plant Cuscuta campestris target host messenger RNAs”的文章。


菟丝子是寄生植物,它们从寄主植物的茎中获取水分和养分,并通过被称为吸器的结构与其宿主交换其他物质。美国宾夕法尼亚州立大学的Michael Axtell 及其同事报道了吸器是如何介导菟丝子的寄生。菟丝子在感染宿主植物的同时在其吸器中累积许多miRNA。这些miRNA然后转移到宿主,在那里它们通过产生次级小干扰RNA和mRNA切割来沉默靶标mRNA。作者还鉴定了菟丝子miRNA靶向的宿主蛋白,并提供证据表明通过miRNA的种间转移对宿主基因表达的这种调节不限于一个宿主。


摘要:

菟丝子是寄生植物,其通过称为吸器的结构从宿主植物的茎获得水分和营养物质。菟丝子吸器促进宿主和寄生植物之间的病毒,蛋白质和mRNA的双向运输,但是这些运输的功能效应是未知的。研究表明,菟丝子在寄生拟南芥时,其吸器处会积累高水平的许多新的miRNAs。许多miRNA长度为22-nt。这种长度的植物miRNA是不常见的,并且与通过二级siRNA 产物放大靶基因的沉默相关联。在寄生过程中,几种拟南芥mRNA被22-nt的菟丝子miRNAs靶向,导致mRNA切割,二次siRNA产生和mRNA积累减少。若宿主编码靶mRNA的两个基因座中具有突变,则能显著促进菟丝子的生长。当菟丝子寄生在拟南芥时,那些表达和激活的miRNA,在感染本氏烟草时也会表达并激活。来自许多其他植物的靶mRNA的同源物,也包含菟丝子miRNA的可能靶点。这些数据表明,菟丝子miRNA作为宿主基因表达的跨物种调节子起作用,并且表明它们可能在寄生过程中充当毒力因子。


Abstract:

Dodders (Cuscuta spp.) are obligate parasitic plants that obtain water and nutrients from the stems of host plants via specialized feeding structures called haustoria. Dodder haustoria facilitate bidirectional movement of viruses, proteins and mRNAs between host and parasite, but the functional effects of these movements are not known. Here we show that Cuscuta campestris haustoria accumulate high levels of many novel microRNAs (miRNAs) while parasitizing Arabidopsis thaliana. Many of these miRNAs are 22 nucleotides in length. Plant miRNAs of this length are uncommon, and are associated with amplification of target silencing through secondary short interfering RNA (siRNA) production . Several A. thaliana mRNAs are targeted by 22-nucleotide C. campestris miRNAs during parasitism, resulting in mRNA cleavage, secondary siRNA production, and decreased mRNA accumulation. Hosts with mutations in two of the loci that encode target mRNAs supported significantly higher growth of C. campestris. The same miRNAs that are expressed and active when C. campestris parasitizes A. thaliana are also expressed and active when it infects Nicotiana benthamiana. Homologues of target mRNAs from many other plant species also contain the predicted target sites for the induced C. campestris miRNAs. These data show that C. campestris miRNAs act as trans-species regulators of host-gene expression, and suggest that they may act as virulence factors during parasitism.








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