Meristematic sculpting in fruit development.

The diversity of shape in life is astounding, and this is particularly vivid when the varied forms observed in our fruit bowls are examined. How some of the tissues of the Arabidopsis fruit are moulded is starting to be understood, revealing how plants may sculpt plant form by modulating the degree of meristematic properties. In this fruit the KNOX I and BLH meristem identity genes promote medial tissue proliferation by maintaining these tissues in a 'quasi-meristematic' fate. The action of these genes is opposed by ASYMMETRIC LEAVES activity that promotes valve formation together with JAGGED/FILAMENTOUS FLOWER and FRUITFULL activities. This is reminiscent of the function of these genes in the shoot apical meristem and in leaf development. In this review, the aim is to present the medial tissues of the Arabidopsis fruit as a modified meristem and extrapolate our knowledge from other plant organs to fruit development.