An auxin‐mediated regulatory framework for wound‐induced adventitious root formation in tomato shoot explants

Abstract

Adventitious roots (ARs) are produced from non‐root tissues in response to different environmental signals, such as abiotic stresses, or after wounding, in a complex developmental process that requires hormonal crosstalk. Here, we characterized AR formation in young seedlings of Solanum lycopersicum cv. ‘Micro‐Tom’ after whole root excision by means of physiological, genetic and molecular approaches. We found that a regulated basipetal auxin transport from the shoot and local auxin biosynthesis triggered by wounding are both required for the re‐establishment of internal auxin gradients within the vasculature. This promotes cell proliferation at the distal cambium near the wound in well‐defined positions of the basal hypocotyl and during a narrow developmental window. In addition, a pre‐established pattern of differential auxin responses along the apical‐basal axis of the hypocotyl and an as of yet unknown cell‐autonomous inhibitory pathway contribute to the temporal and spatial patterning of the newly formed ARs on isolated hypocotyl explants. Our work provides an experimental outline for the dissection of wound‐induced AR formation in tomato, a species that is suitable for molecular identification of gene regulatory networks via forward and reverse genetics approaches.