FveRGA1, encoding a DELLA protein, negatively regulates runner production in Fragaria vesca

FveRGA1 was highly expressed in tender tissues such as young leaves and stem apices and was localized in the nucleus. RNAi silencing of FveRGA1 in non-runnering woodland strawberry produced many runners. FveRGA1 is thus a key gene controlling strawberry runner formation. The propagation of strawberry is mainly based on runners, while the genes controlling runner production have not been well characterized. Exogenous applications of optimum concentration gibberellins (GAs) promote runner formation in strawberry cultivation and GA can accelerate the degradation of DELLA proteins. To investigate whether DELLA proteins are responsible for runner production, we analyzed all the DELLA genes in Fragaria vesca and cloned a DELLA protein-encoding gene FveRGA1 in woodland strawberry using RT-PCR. Subcellular localization analysis indicated that FveRGA1 was localized in the nucleus. A transcription analysis suggested that FveRGA1 was expressed ubiquitously in all examined strawberry organs, especially in young leaves, petioles, and stem apices. RNA interference (RNAi) technology was carried out to investigate the function of FveRGA1 in woodland strawberry 'Yellow Wonder' (YW) and 'Ruegen' (RG) via an Agrobacterium-mediated transformation. Interestingly, the RNAi silencing transgenic plants in the naturally non-runnering YW and RG strains produced many runners, suggesting FveRGA1 as a key gene controlling strawberry runner formation. Our study lays a solid basis for unraveling the detailed molecular mechanism of runner formation in strawberry.