Reductions of Endogenous Gibberellin Content Impact Fruit Development and Modify Tomato Fruit Metabolism During Ripening

Gibberellins (GAs) play a crucial role in modulating developmental processes throughout the plant life cycle. They are particularly significant during the transition and maintenance of the reproductive meristem, as well as in facilitating the development of floral organs. Additionally, GAs regulate the early stages of fruit development, in coordination with auxin and cytokinin, likely due to their involvement in both division and cell expansion. However, it remains unclear whether fluctuations in endogenous GA levels influence fruit development and metabolism during ripening. To address this, we investigated tomato mutant plants deficient in GAs biosynthesis (gib3, moderately deficient; gib2, intermediate deficiency and gib1, extremely deficient in GAs). Notably, gib2 and gib1 mutants were characterized by a complete interruption of their reproductive development at the floral bud level. Although gib3 plants displayed a slight delay in fruit development, at the end of fruit ripening both wild type (WT) and gib3 fruits were highly similar. Only minor differences were found between WT and gib3 mutant plants in terms of floral development and total fruit yield. Our findings revealed that reduced GA levels in gib3 mutant did not result in morphological modifications in fruits, and relatively few metabolic changes were observed between genotypes during fruit ripening. Typical metabolic changes during ripening, including increments in amino acids and soluble sugars along with decreases in starch, were observed. Collectively, our study demonstrate that GAs play a crucial role in transitioning plants from the vegetative to reproductive stage and in initiating fruit set. Tomato plants with reduced endogenous content of gibberellins show interruption or delay of the reproductive stage.