Spatially organizing million callus cells identify the core-network enable tomato shoot regeneration [scRNA-Seq]

Unlike animals, depending on pre-existing stem cell niches, plants re-establish pluripotency de novo. Although current understanding emphasizes hormonal control and external environmental cues, a unifying framework that explains how millions of cells coordinate fate decisions across space and time remains elusive.

Here, we construct a million-cell spatial transcriptomic atlas of plant regeneration, achieving mesoscale resolution observation for all stages of tomato callus development. This atlas reveals a tripartite stem cell niche architecture: an outer signaling layer, intermediate plastic zone, and a quiescent core, features reminiscent of animal regenerative niches. We uncover a fundamental Inducer-Maintainer-Trigger (IMT) triad model, wherein PI-2 (Inducer) establishes a stem cell activating microenvironment, DCL2/22-nt siRNAs (Maintainer) safeguard pluripotency through post-transcriptional regulation, and EPFL8 (Trigger) initiates stem cell niche establishment.