Species-specific microRNA discovery and target prediction in the Soybean Cyst Nematode

The soybean cyst nematode (SCN) is a devastating pathogen for economic and food security considerations. Although the SCN genome has recently been sequenced, microRNA (miRNA) has not been systematically explored and reported. This paper describes the development of a species-specific SCN miRNA discovery pipeline and its application to the SCN genome. Experiments on well-documented nematodes (Caenorhabditis elegans and Pristionchus pacificus) are used to tune the pipeline’s hyperparameters and confirm its recall and precision. Application to the SCN genome identifies 1,565 high-confidence putative SCN miRNA. Prediction specificity within SCN is confirmed by applying the pipeline to RNA hairpins from known exonic regions of the SCN genome. Prediction recall is confirmed by building a positive control set of SCN miRNA, based on sequence and structure homology with known miRNA from other nematodes. Interestingly, a number of novel miRNA are predicted to be encoded within the intronic regions of effector genes, known to be involved in SCN parasitism, suggesting that these miRNA may also be involved in the infection process or virulence. Beyond miRNA discovery, gene targets within SCN are predicted for all high-confidence novel miRNA using a miRNA-mRNA target prediction system. Lastly, cross-kingdom miRNA targeting is investigated, where putative soybean mRNA targets are identified for novel SCN miRNA. All predicted miRNA and gene targets are made available in supplementary materials and through this repository