Water availability determines plant regeneration fates

Wounding and hormones serve as diverse triggers for regeneration in animals and plants but how organisms determine regeneration outcomes remains largely unknown. Here, we demonstrated that wounded Arabidopsis tissues regenerate two distinct fates, wound-induced callus or de novo root formation, that are driven by antagonizing molecular pathways related to cambium and root development. We discovered that local water availability dictated these regeneration outcomes in Arabidopsis and tomato, with high water triggering root fate and low water initiating callus fate. Moreover, distinct spatial distributions of auxin response maxima were critical for fate progression and water availability regulated these auxin maxima through the hormones ethylene and jasmonic acid. We propose that water availability determines environmental control of regeneration plasticity with applied potential for improving regeneration in agriculture.