The fruit is arguably one of the most complex plant structures, consisting of numerous distinct tissue types and where many morphogenetic events take place in an exquisitely harmonized manner. This organ protects and nourishes the developing ovules and seeds, ensuring and providing the means for their dispersal. Moreover, fruits are the harvested products for many food crop plant species, playing a central role in agriculture. For decades, the fruit of Arabidopsis thaliana (a Brassicaceae) has been used as reference to dissect different developmental programs during fruit morphogenesis. The Arabidopsis thaliana fruit displays three major tissue domains easily distinguished from the outside: the valves, the valve margins and the replum. The formation of these tissues is mediated by a sophisticated network of regulatory genes, and recent studies have shown that microRNAs play crucial roles in this process. However, the lack of loss-of-function mutants in miRNA-encoding genes represented a challenge to certainly assign their functions in the fruit.

On the other hand, whereas a wealth of information has been accumulated over the years on the roles of small regulatory peptides during plant development, our knowledge on how they may impact fruit morphogenesis is very limited.

In this context, we decided to implement a CRISPR/Cas9 genome editing approach to interrogate the functions of genes encoding for miRNA and small signaling peptides, hoping to further broaden our current understanding of fruit development.