Effects of Low-Molecular-Weight RNA and Temperature on Tomato Bushy Stunt Virus Symptom Expression

Abstract

Low-MW RNA associated with tomato bushy stunt virus (TBSV) infection altered symptom expression is several experimental hosts. The linear, single-stranded, low-MW RNA was encapsidated in TBSV-encoded protein. In addition, infected tissue contained a tube-stranded (ds) form of this molecule. The most obvious symptom modification induced by the low-MW RNA was attenuation in Nicotiana clevelandii. At elevated temperatures (27.degree. C), symptoms induced by TBSV alone and in combination with the low-MW RNA differed from those induced at a lower temperature (16.degree. C). In N. clevelandii, high temperature attenuation of symptoms was similar, but not identical to, that caused by the low-MW RNA. This symptom change was associated with changes in the ds [double stranded]RNA species accumulating in N. clevelandii as a result of virus infection. Among these changes was the suppression of low-MW RNA replication.