Tomato floral induction and flower development are orchestrated by the interplay between gibberellin and two unrelated microRNA‐controlled modules

Summary Age‐regulated micro RNA 156 (miR156) and targets similarly control the competence to flower in diverse species. By contrast, the diterpene hormone gibberellin (GA) and the micro RNA 319‐regulated TEOSINTE BRANCHED / CYCLOIDEA / PCF ( TCP ) transcription factors promote flowering in the facultative long‐day Arabidopsis thaliana , but suppress it in the day‐neutral tomato ( Solanum lycopersicum ). We combined genetic and molecular studies and described a new interplay between GA and two unrelated mi RNA ‐associated pathways that modulates tomato transition to flowering. Tomato PROCERA / DELLA activity is required to promote flowering along with the miR156‐targeted SQUAMOSA PROMOTER BINDING – LIKE ( SPL / SBP ) transcription factors by activating SINGLE FLOWER TRUSS ( SFT ) in the leaves and the MADS ‐Box gene APETALA 1 ( AP 1 ) / MC at the shoot apex. Conversely, miR319‐targeted LANCEOLATE represses floral transition by increasing GA concentrations and inactivating SFT in the leaves and AP 1/ MC at the shoot apex. Importantly, the combination of high GA concentrations/responses with the loss of SPL / SPB function impaired canonical meristem maturation and flower initiation in tomato. Our results reveal a cooperative regulation of tomato floral induction and flower development, integrating age cues (miR156 module) with GA responses and miR319‐controlled pathways. Importantly, this study contributes to elucidate the mechanisms underlying the effects of GA in controlling flowering time in a day‐neutral species.