Cellular mechanisms of plant tissue regeneration: head over heals

Plants are remarkable at healing. Humankind has long known about this and has exploited it by grafting different plants together for crop propagation and crop improvement. During graft formation, the surfaces of the cut tissues attach, the cells proliferate, and the vasculatures reconnect to form a chimeric plant. Although grafting is extensively used in fruit and vegetable crop production, our fundamental understanding of how a graft forms is limited. In this current thesis, we described the cellular mechanisms of graft regeneration. We found that auxin signalling is crucial in the procambial cells during tissue adhesion, callus formation, phloem reconnection, to form a successful graft connection (Paper I). Investigating the effects of environmental factors on graft regeneration demonstrated that high temperatures promoted graft formation via leaf-derived auxin signaling (Paper II). Additionally, we found that plant parasitism, a grafting-like process, also shared a common feature by enhancing inter-plant vascular connections upon elevated temperatures. Lastly, we showed that parasitic plants regulated their infection organ development in the presence of nitrogen via abscisic acid (Paper III). Altogether, the work in this thesis expands our fundamental knowledge of tissue regeneration by highlighting plant’s developmental plasticity.