Viruses isolated from single necrotic lesions in Chenopodium quinoa were used to infect tobacco plants and virions were extracted following the appearance of symptoms (1). A region encompassing genome positions 7808 to 9437 was amplified by high-fidelity RT-PCR and 83 molecular clones were sequenced (T_s = 4890). Only four substitutions were observed. Using Equation 6, max[m_s/n/c] = 3 ´ 4 / 83 / 4890 = 3.0 ´ 10^-5. Another reason to consider this estimate as an upper-limit is that the observed rate was close to the rate of RT-PCR errors.

1. Sanjuán, R., P. Agudelo-Romero, and S. F. Elena. 2009. Upper-limit mutation rate estimation for a plant RNA virus. Biol. Lett. 5:394-396.