Modification of Plant Pre-cultivation in Vitro Alters Regeneration Competence in Recalcitrant Model Andean Potato

Planta ssp. andigena line 7540, a key model for tuberization, exhibits a recalcitrance to Agrobacterium-mediated transformation. This study aimed to improve leaf regeneration efficiency by optimizing the source plant'sin vitro pre-cultivation: control conditions (non-permeable lids, 2% sucrose) versus mixotrophic and photoautotrophic regimes (air-permeable lids, 2% or 0% sucrose, respectively). The use of air-permeable lids significantly increased biomass and proportion of leaves ≥0,5 cm2. Moreover, we found a link between plant pre-cultivation, leaf physiological state and regeneration potential. In photoautotrophic plants, regeneration competence was strongly favoured in leaf explants from upper half of source plants, while predominantly heterotrophic control exhibited an opposite behaviour. Mixotrophic variant preserved regeneration competence along the shoot axis. In conclusion, the competence for regeneration varies with tissue physiological status and thus can be shifted via low-input adjustment of the source plant pre-cultivation. This approach might prove beneficial also for regeneration of other recalcitrant crops.