Ancient trans-Acting siRNAs Confer Robustness and Sensitivity onto the Auxin Response

• DOI: 10.1016/j.devcel.2016.01.010
• Publication Date: 2016-02-08T16:52:40Z
• Authors: Yevgeniy Plavskin; Akitomo Nagashima; Pierre-François P...; Mitsuyasu Hasebe; Ralph S. Quatrano; Gurinder S. Atwal; Marja C.P. Timmer...
• Keywords: 0303 health sciences; Indoleacetic Acids; Physcomitrella; gene regulatory network; MicroRNAs; 03 medical and health sciences; Gene Expression Regulation, Plant; RNA, Plant; evolution; small RNA; Gene Regulatory Networks; RNA, Small Interfering; auxin; Developmental Biology; Plant Proteins; Signal Transduction

ABSTRACTNovel developmental programs often evolve via cooption of existing genetic networks. To understand this process, we explored cooption of theTAS3tasiRNA pathway in the mossPhyscomitrella 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.