Research Team Identifies Gene Responsible for Diversity of Fruit Shapes in Brassicas

The Brassicaceae family has a stunning diversity of fruit shapes, and in this family, the heart-shaped seed pods of the Capsella genus stand out. Eight million years ago, Capsella embarked on a different evolutionary pathway from its close relatives Arabidopsis and Camelina. This led to different shapes in the fruits which in these plants form pods enclosing the seeds before dispersal. Arabidopsis fruits are cylindrical, Camelina's are spherical, while the Capsella's are heart-shaped.

A research team from John Innes Centre (JIC) used gene editing technology, transgenic plants, and molecular reporting techniques to show that the gene INDEHISCENT (IND) lay at the heart of the matter. In Arabidopsis, this gene is found only in strips of cells that regulate seed dispersal or pod shatter. However, in Capsella, IND has expanded local expression into the upper part of the valves, the shoulders that give the plant its characteristic heart shaped fruits. The gene-edited mutant Capsella without the IND gene showed significantly reduced shoulders compared to the wild type.

Previous studies have showed that IND regulates the plant hormone auxin. JIC Prof. Lars Ostergaard said that while IND is important for the Capsella fruit shape, it mediates its effects by directly upregulating auxin biosynthesis in these pods to pilot growth.

Read more details in the JIC press release.