Milos Tanurdzic - Large genomes and small RNA: Transcriptome reprogramming by planthormone signaling in plant development

We are exploringhow plants execute and fine-tune their developmental programs in response tointernal and external cues that rely on plant hormone signaling. In particularwe are interested in the transcriptional and post-transcriptional regulationduring early developmental decisions, such as giberellic acid (GA)-regulatedsex determination in 3-6 cell fern gametophytes, or strigolactone (SL)-inducedrepression of branching via arrest of axillary meristems in garden pea. Ourexperimental approaches rely on next generation sequencing to identify andquantify coding and non-coding transcripts in plants without reference genomesequence (but otherwise excellent model organisms). I will illustrate how planthormones can have very different effects on gene expression throughoutdevelopment. In fern gametophytes GA induces extensive transcriptome (andlikely epigenome) reprogramming, where we discovered over 1100 genes affectedby GA, mostly up-regulated, including signatures of extensive chromatinremodeling, activation of several hormone signaling cascades, and extensivechanges in non-coding RNA, including microRNA, well before any morphologicaldifferences can be observed. In contrast, we found that SL induces small butvery fast and specific transcriptional responses in garden pea axillary buds,including several key transcription factors, implicating other hormonesignaling pathways, as well as post-transcriptional and post-translationalcontrol in the regulation of branching.