Rice Lateral Root Inducible System timeseries
To transcriptionally characterize lateral root development in rice, we subjected the rice LRIS to genome-wide transcript profiling via RNA-sequencing. Taking into account the appearance of the first (stage I primordium) cell divisions starting from 6 hours after NAA treatment, we sampled at 2 hours and at 5 hours after NAA treatment to capture the primary auxin response and the gene expression related to initiation, respectively. Additionally, we sampled at 8 hours, 14 hours and 20 hours, in which the root was highly enriched for stage I, II and III primordia, respectively. As the spatiotemporal assessment of the primordia in the LRIS showed a highly synchronous induction and development of lateral roots in particular in the region just above the root meristem, root sections between 750 µm and 2000 µm from the root tip were microdissected and used for RNA-extraction. To assess possible artefacts induced by the replacement of the medium, we sampled a control before and 2 hours after replacement with NPA containing medium.