Most multi-cellular organisms have a capacity to regenerate lost features, however, few have the ability to regenerate an entirely new body plan from differentiated tissue. Induction of new shoot apical meristems (SAMs) from cultured root explants is a widely used but poorly understood plant regeneration system in which new plants are regenerated from adult somatic tissue. We have characterized early patterning events during regeneration of the Arabidopsis SAM using fluorescent reporters of gene and protein activity known to be required for proper embryonic development. We have found that the early patterning of the new SAM can be broken down into stereotypic stages of PIN-FORMED1 (PIN1), SHOOTMERISTEMLESS (STM), WUSCHEL (WUS), CUP-SHAPED COTYLEDON 2 (CUC2), FILAMENTOUS (FIL), REVOLUTA (REV), and CLAVATA3 (CLV3) expression and activity. We have discovered that new shoot meristems are derived from small number of initial cells via a patterning process in which relative temporal gene expression is analogous to embryogenesis, in contrast to spatial gene expression, which strongly deviates from embryonic patterning. We are further characterizing the shoot regeneration system to support its use as an assay for studying specific aspects of early developmental patterning and an accessible system for the investigation of complex regeneration in the well studied model organism Arabidopsis.

In addition, exogenous hormonal cues dictate the ability of Arabidopsis to regenerate. Therefore, we are also investigating the requirement of proper hormone transport in the regeneration process, using both mutants with impaired hormone transport and chemical inhibitors of hormone transport.