Apple chlorotic fruit spot viroid: a putative new pathogenic viroid on apple characterized by next-generation sequencing.

Viroid-like symptoms were observed in 2016 on apple fruits of the cultivar "Ilzer Rose" in southern Burgenland, Austria. Preliminary molecular biological investigations indicated that the symptoms were caused by a new unknown viroid. Therefore, new primers were designed, and the whole genome sequence of the viroid (354 nt) was determined by next-generation amplicon sequencing using the Illumina MiSeq® platform (San Diego, California, USA). The viroid secondary structure has a rod-like conformation and contains conserved regions (the TCR, CCR upper strand, and CCR lower strand) that are characteristic of members of the genus Apscaviroid. Based on our results and the demarcation criteria for viroids, the tentatively named "apple chlorotic fruit spot viroid" should be considered a putative new member of the genus Apscaviroid.