PT  - JOURNAL ARTICLE
AU  - Yevgeniy Plavskin
AU  - Akitomo Nagashima
AU  - Pierre-François Perroud
AU  - Mitsuyasu Hasebe
AU  - Ralph S. Quatrano
AU  - Gurinder S. Atwal
AU  - Marja C.P. Timmermans
TI  - Ancient <em>trans</em>-acting siRNAs Confer Robustness and Sensitivity onto the Auxin Response
AID  - 10.1101/024307
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 024307
4099  - http://biorxiv.org/content/early/2016/02/01/024307.short
4100  - http://biorxiv.org/content/early/2016/02/01/024307.full
AB  - Novel developmental programs often evolve via cooption of existing genetic networks. To understand this process, we explored cooption of the TAS3 tasiRNA pathway in the moss Physcomitrella patens. We find an ancestral function for this repeatedly redeployed pathway in the spatial regulation of a conserved set of Auxin Response Factors. In moss, this results in stochastic patterning of the filamentous protonemal tissue. Through modeling and experimentation, we demonstrate that tasiRNA regulation confers sensitivity and robustness onto the auxin response. Increased auxin sensitivity parallels increased developmental sensitivity to nitrogen, a key environmental signal. We propose that the properties lent to the auxin response network, along with the ability to stochastically modulate development in response to environmental cues, have contributed to the tasiRNA-ARF module’s repeated cooption during evolution. The signaling properties of a genetic network, and not just its developmental output, are thus critical to understanding the evolution of multicellular forms.