“…A pioneering work of Kreuze et al (2009) and the follow-up studies listed in Supplementary Tables S1 , S2 and discussed below have established that both RNA and DNA viruses as well as viral satellites and viroids can be identified and their genomes partially or fully reconstructed by deep sequencing and bioinformatic analysis of small RNA population (small RNA-ome) from an infected plant. Likewise, small RNA deep sequencing can be used for virus detection and assembly of viral genomes from fungi ( Vainio et al, 2015 ; Yaegashi et al, 2016 ; Donaire and Ayllón, 2017 ; Velasco et al, 2018 ) and from invertebrate animals ( Wu et al, 2010 ; Aguiar et al, 2015 ; Fung et al, 2018 ), including insect vectors of the plant viruses transmitted in a propagative manner ( Xu et al, 2012 ; Fletcher et al, 2016 ; de Haro et al, 2017 ). Such universality of the small RNA-omics approach for virus diagnostics is based on evolutionary conservation of the small RNA-generating RNA interference (RNAi) and gene silencing machinery that regulates gene expression and defends against invasive nucleic acids such as transposons, transgenes and viruses in most eukaryotes ( Ghildiyal and Zamore, 2009 ; Nayak et al, 2013 ; tenOever, 2016 ).…”