【原】PaperRSS文献速递|大麦（Hordeum vulgare）胞外囊泡的分离、鉴定及其在基于RNAi的作物保护中的作用

PaperRSS 2021-04-30

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喷雾诱导的基因沉默(SIGS)可以绕过费时费力的双链 RNA 转基因表达诱导致病原靶基因沉默，从而获得强大的抗病能力，这是一个突破性的发现。然而，未来的野外应用将需要对 dsRNA 的吸收、加工和转移有基本的机械知识。越来越多的证据表明，在宿主诱导的基因沉默(HIGS)中，细胞外小泡(EVs)介导转基因小干扰 rna (si)的转移。在这里，我们研究了肠道内皮细胞的作用对于大麦(Hordeum vulgare)向目标真菌禾谷镰刀菌(Fusarium graminearum)转运喷洒 dsRNA 的影响。我们发现大麦156nm 大小的 EVs 主要包含21和19个核苷酸(nt) siRNAs，起始于5’末端 Adenine。

值得注意的是，与从转基因拟南芥 HIGS 中分离的 EVs 相比，大麦 EVs 含有较少的 siRNA。我们的研究结果进一步支持了HIGS和SIGS应用之间的机制差异，以及ev在SIGS中的次要作用。

图采用2% 乙酸铀酰将大麦 EVs 负染于聚乙二醇网片上

Abstract：

The demonstration that spray-induced gene silencing (SIGS) can confer strong disease resistance bypassing the laborious and time-consuming transgenic expression of double-stranded (ds)RNA to induce gene silencing of pathogenic targets was groundbreaking. However, future field applications will require fundamental mechanistic knowledge on dsRNA uptake, processing, and its transfer. There is increasing evidence that extracellular vesicles (EVs) mediate the transfer of transgene-derived small interfering (si)RNAs in host-induced gene silencing (HIGS) applications. Here, we examined the role of EVs regarding the translocation of sprayed dsRNA from barley (Hordeum vulgare) to the target fungus Fusarium graminearum. We found barley EVs with 156 nm in size containing predominantly 21 and 19 nucleotide (nt) siRNAs starting with a 5’-terminal Adenine. Notably, barley EVs contain less siRNA compared to EVs isolated from transgenic HIGS Arabidopsis plants. Together our results further underpin mechanistic differences between HIGS and SIGS applications and a minor role of EVs in SIGS.