Novel natural genetic variation controlling the competence to form adventitious roots and shoots from the tomato wild relative Solanum pennellii

Tomato (Solanum lycopersicum L.) is an attractive model to study the genetic basis of adventitious organ formation capacity, since there is considerable natural genetic variation among wild relatives. Using a set of 46 introgression lines (ILs), each containing a small chromosomal segment of Solanum pennellii LA716 introgressed and mapped into the tomato cultivar M82, we characterized a high shoot-regeneration capacity for ILs 3-2, 6-1, 7-1, 7-2, 8-2, 8-3, 9-1, 9-2, 10-2 and 10-3, when cotyledon explants were cultivated on medium containing 5.0μM BAP. F1 seedlings from the crosses ‘Micro-Tom×ILs’ and ‘ILs×ILs’ demonstrated that the shoot regeneration capacity of most ILs was dominant and that the regeneration ability of IL8-3 enhanced that of the other ILs in an additive manner. The ILs 3-2, 7-1, 8-3, and 10-2 also exhibited enhanced root formation on MS medium containing 0.4μM NAA, indicating that these chromosomal segments may contain genes controlling the competence to assume distinct cell fates, rather than the induction of a specific organ. We also performed the introgression of the genes controlling competence into the model system ‘Micro-Tom’. The further isolation of such genes will improve our understanding of the molecular basis of organogenic capacity.