Unravelling the trans-kingdom function of Sstrf2, tRNA-derived small RNA of Sclerotinia sclerotiorum

In Sclerotinia sclerotiorum, white mold fungus, tRNA-derived small RNAs (tRFs) potentially belong to a new class of virulence effector because we previously reported two very abundant of larger size at 28-30 nt. In this study, we show that the tRFs have no fungal targets predicted based on transcriptome, degradome and small RNA-Seq of S. sclerotiorum. The tRFs function in a trans-kingdom manner was also evidenced by immunoprecipitation of argonaute protein 1 (Ago1) profiled by small RNA-Seq, as well as A. thaliana ago1 knockout mutant is more tolerant to DK3 inoculation.

核盘菌（Sclerotinia sclerotiorum，又称白霉真菌）中，转运RNA衍生小RNA（tRNA-derived small RNAs，tRFs）可能属于一类新型致病效应因子——此前我们曾报道该菌中存在两类丰度极高、长度为28~30 nt的较大尺寸tRFs。本研究基于核盘菌的转录组、降解组及小RNA测序数据进行预测分析，未发现此类tRFs存在真菌内源靶标。此外，通过小RNA测序分析的Argonaute蛋白1（Argonaute protein 1, Ago1）免疫沉淀实验，证实了tRFs的跨界作用功能；同时，拟南芥（A. thaliana）ago1基因敲除突变体对DK3菌株接种的耐受性更强。