Deep sequencing analysis of a strain of pecan mosaic-associated virus infecting Atractylodes macrocephala Koidz

Leaves of Atractylodes macrocephala Koidz with virus-like symptoms were collected in Shanxi Province, China. The strain Am of the Potyvirus species, pecan mosaic-associated virus (PMaV-Am), was discovered through the assembly of virus derived small interfering RNAs (vsiRNAs) that were isolated from symptomatic samples. The complete genome of PMaV-Am was determined to be 9310 nucleotides (nt) in length, including a large open reading frame encoding a polyprotein. Phylogenetic analysis showed that PMaV-Am is clustered together and most closely related to strain PMaV-LA from pecan. Sequence alignments of PMaV-Am complete genomic RNAs with PMaV-LA showed 98.78% nucleotide sequence homology and 96.53% amino acid identity, respectively. Further analyses of the vsiRNA profile showed that the most abundant PMaV from A. macrocephala (PMaV-Am) vsiRNAs were 21 nt long and biased for A at their 5 'terminal residue. Polarity distribution revealed that vsiRNAs were nearly equal amount of sense and antisense strands and hotspot was distributed in the HC-Pro coding region of the PMaV-Am genome. These results might provide an insight into the host RNA silencing defense induced by PMaV-Am, and provide guidelines on designing antiviral strategies using RNAi against PMaV-Am.