Local auxin biosynthesis is required for root regeneration after wounding (Nature Plants)

During root development, auxin accumulates at the stem cell niche (SCN) located at the root meristem. Both polar auxin transport and local auxin biosynthesis contribute to the auxin accumulation. During root regeneration after wounding, the source of auxin accumulation is still a question. To address that, Matosevich et al. used an inhibitor of local auxin biosynthesis, L-Kynurenine (L-Kyn), and showed that addition of L-Kyn causes dose-dependent complete loss of regeneration on root cuts.  Further analysis of transcriptome time series data on root cuts treated with L-Kyn showed downregulation of auxin-response and regeneration-induced genes, which indicates the role of local auxin biosynthesis in initial wound response and early cell division. The authors also showed the role of local auxin synthesis for tissue pattern identity at later stages of regeneration by using the reporter constructs driven by quiescent-center specific promoter, WOX5, and endodermis specific promoter, SCN. Finally, the authors showed the involvement of ERF115, a regeneration competence factor, in activating the local auxin biosynthetic genes. Overall, the authors in this paper showed that long term stable accumulation of auxin through local auxin biosynthesis is required for root regeneration after wounding. (Summary by Sunita Pathak @psunita980)  Nature Plants 10.1038/s41477-020-0737-9