Fruit formation involves development of:
Fruit formation predominantly involves development of ovary after successful fertilization triggered by hormonal signals including auxin, gibberellin, and cytokinin produced by developing seeds preventing abscission zone activation and stimulating cell division and expansion programs. Ovary wall differentiates into pericarp comprising exocarp, mesocarp, and endocarp whose texture, lignification, and sugar content define fleshy drupes and berries versus dry dehiscent or indehiscent pods. Accessory tissues like receptacle may contribute forming pome or aggregate fruits. Maturation ensures coordinated seed protection and effective dispersal via animal ingestion or wind currents.
Ref: Gillaspy et al., Plant Cell 1993: fruit formation involves ovary development after fertilization driven by auxin/GA signals.