Replication competence served as a driving force for experimental evolution of a satellite RNA associated with Bamboo mosaic virus
S. LEE (1), I. Wang (2), M. Liu (3), Y. Hsu (3), N. Lin (4) (1) Institute of Plant and Microbial Biology, Academia Sinica, Taiwan; (2) Department of Biological Sciences, University at Albany, U.S.A.; (3) Graduate Institute of Biotechnology, National Chung Hsing University, Taiwan; (4) Institute of Plant and Microbial Biology, Academia Sinica, Taiwan

Genetic mutation is one of the driving forces for evolution. RNA viruses are highly mutable, thus can accumulate advantageous mutations when adapting to different environmental cues. Here, we showed how a satellite RNA (satRNA), parasite of virus, evolved mutations experimentally. We chose satellite RNA associated with Bamboo mosaic virus (satBaMV), which totally depends on its cognate helper virus (HV) for replication and encapsidation, as a working material, and assayed its evolutionary dynamics under different replication stresses. Specifically, we serially passaged a prototype satBaMV isolate on (1) wild-type plants co-infected with BaMV or (2) transgenic tobacco plants expressing entire BaMV genome. Deep sequencing revealed the evolutional dynamics with increased mutation frequencies and population diversity in a passage-dependent manner. The patterns of genetic variations of satBaMV populations were markedly different among different stresses and passages. Notably, there were four significant and dominate mutations identified, which were located in the 5’ untranslated region (UTR) of satBaMV.  One of the single-nucleotide substitutions (82U to C) of satBaMV is the key determinants involved in the replication competence between satBaMV and BaMV. By in vivo competition assays at single cell levels, we showed that evolved satBaMV winners with two single-nucleotide substitutions are consistent with those found in passaged plants. In addition, we observed the differential mutation patterns in inoculation leaves and systemic leaves, indicating the preferential mutations for satBaMV to adapt different replication and movement stresses in vivo.

Abstract Number: P13-412
Session Type: Poster