Symptom-modulating properties of peanut stunt virus satellite RNA sequence variants.

The symptom-modulating properties of three peanut stunt virus (PSV) satellite RNA (satRNA) sequence variants were studied. The (V)-satRNA did not affect symptom development in tobacco plants infected with PSV. The (G)- or (WC)-satRNA, on the other hand, attenuated the symptoms. In these plants, the symptoms of PSV were restricted primarily to the inoculated leaves, and in some cases, a few leaves above the inoculated leaf showed small chlorotic areas. Northern blot analysis of total nucleic acids from PSV-infected plants containing the (V)-satRNA revealed the presence of both satellite and viral RNAs in inoculated leaves as well as in systemically infected leaves. On the other hand, satellite and viral RNAs were detected in the inoculated but not in the noninoculated leaves from infected plants containing either (G)- or (WC)-satRNA. Although a decrease in the quantities of genomic RNAs 1, 2, and 3 was characteristic of all satRNA-containing plants, this effect was more evident in the case of (G)- and (WC)-satRNAs. The complete nucleotide sequences of the three satRNAs were determined and compared to the published sequence of PSV satRNA. The (V)-satRNA differed from the published sequence at two positions, whereas the (G)- and (WC)-satRNAs differed at six and eight positions, respectively. Comparison of the nucleotide sequence of the satRNA having no effect on PSV-induced symptoms with those reducing virus symptoms suggests that a single nucleotide change or as many as five nucleotide changes may distinguish between attenuating and nonattenuating satRNAs.