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
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.