Derbyshire Mark, Mbengue Malick, Barascud Marielle, Navaud Olivier, Raffaele Sylvain
Centre for Crop and Disease Management, Curtin University, Perth, Western Australia, Australia.
Laboratoire des Interactions Plantes Micro-organismes, INRA, CNRS, Université de Toulouse, Castanet Tolosan, France.
Mol Plant Pathol. 2019 Sep;20(9):1279-1297. doi: 10.1111/mpp.12841. Epub 2019 Jul 30.
Fungal plant pathogens secrete effector proteins and metabolites to cause disease. Additionally, some species transfer small RNAs (sRNAs) into plant cells to silence host mRNAs through complementary base pairing and suppress plant immunity. The fungus Sclerotinia sclerotiorum infects over 600 plant species, but little is known about the molecular processes that govern interactions with its many hosts. In particular, evidence for the production of sRNAs by S. sclerotiorum during infection is lacking. We sequenced sRNAs produced by S. sclerotiorum in vitro and during infection of two host species, Arabidopsis thaliana and Phaseolus vulgaris. We found that S. sclerotiorum produces at least 374 distinct highly abundant sRNAs during infection, mostly originating from repeat-rich plastic genomic regions. We predicted the targets of these sRNAs in A. thaliana and found that these genes were significantly more down-regulated during infection than the rest of the genome. Predicted targets of S. sclerotiorum sRNAs in A. thaliana were enriched for functional domains associated with plant immunity and were more strongly associated with quantitative disease resistance in a genome-wide association study (GWAS) than the rest of the genome. Mutants in A. thaliana predicted sRNA target genes SERK2 and SNAK2 were more susceptible to S. sclerotiorum than wild-type, suggesting that S. sclerotiorum sRNAs may contribute to the silencing of immune components in plants. The prediction of fungal sRNA targets in plant genomes can be combined with other global approaches, such as GWAS, to assist in the identification of plant genes involved in quantitative disease resistance.
植物真菌病原体分泌效应蛋白和代谢产物来引发疾病。此外，一些物种会将小RNA（sRNA）转移到植物细胞中，通过互补碱基配对使宿主mRNA沉默，从而抑制植物免疫。核盘菌可感染600多种植物，但对于其与众多宿主相互作用的分子过程却知之甚少。特别是，缺乏核盘菌在感染过程中产生sRNA的证据。我们对核盘菌在体外以及感染两种宿主植物（拟南芥和菜豆）过程中产生的sRNA进行了测序。我们发现，核盘菌在感染过程中至少产生374种不同的高丰度sRNA，其中大部分源自富含重复序列的可塑性基因组区域。我们预测了这些sRNA在拟南芥中的靶标，发现这些基因在感染过程中的下调程度明显高于基因组的其他部分。在全基因组关联研究（GWAS）中，拟南芥中核盘菌sRNA的预测靶标富含与植物免疫相关的功能域，并且与数量抗病性的关联比基因组的其他部分更强。拟南芥中预测的sRNA靶标基因SERK2和SNAK2的突变体比野生型更易受核盘菌感染，这表明核盘菌sRNA可能有助于沉默植物中的免疫成分。在植物基因组中预测真菌sRNA靶标可以与其他全局方法（如GWAS）相结合，以协助鉴定参与数量抗病性的植物基因。
