The phytohormone auxin is an important signaling molecule for all land plants, which regulates various developmental processes including cell division pattern and elongation toward the light (Kato et al., 2017). Past studies in angiosperms have revealed the basic molecular mechanism for auxin signaling mediated by AUXIN RESPONSE FACTOR (ARF) transcription factors. How do ARFs specify various auxin responses? Angiosperms have many ARF genes in the genome (e.g. 23 in Arabidopsis, 25 in rice), which are phylogenetically classified into three classes A, B and C. It is thought that functional diversification of ARFs enable to create different responses, but detail of the differences between three classes are not clear enough. In addition, high genetic redundancy in angiosperms often become a barrier for genetic experiments. To solve these problems, we utilize the bryophyte Marchantia polymorpha as model organism. M. polymorpha has a simple auxin system with only three ARFs which belong to each of three major classes (Kato et al., 2015). Our research aim is to understand the basics of the functional difference between three classes of ARF in land plants, their impact on transcriptional responses, and the changes during the evolution.
Techniques used: CRISPR/Cas9-mediated mutagenesis, Agrobacterium-mediated transformation, RNA-sequencing, confocal microscopy.
Kato et al. (2015) PLoS Genet. 11, e1005084.
Kato et al. (2017) J. Exp. Bot. doi: 10.1093/jxb/erx267