Jan 12 2011 | Posted by SSBibek

The Battle of the Sexes

Scientists have uncovered a rare insight into a war between genes to control the sex of a plant.

The researchers, from the ARC Centre of Excellence in Plant Energy Biology and the School of Biomedical, Biomolecular and Chemical Sciencesat The University of Western Australia, have described the evolution of a ‘restorer to fertility’ (Rf) gene that influences sex determination.

The findings, published this week in the prestigious journal Proceedings of the National Academy of Sciences, have important implications for agricultural science and medicine.

Plant cells, like human cells, contain tiny mitochondria that produce energy for the cell.  Mitochondria are thought to be descended from bacteria that entered the cell more than two billion years ago and contain their own genes.  Some of these genes produce proteins which can turn a hermaphrodite plant into a female by preventing the male parts of the flower from forming.

Researcher Dr Sota Fujii said: “Mitochondria are more likely to pass on their genetic information when the plant is female.”

However, plants have a defence mechanism, according to the published paper.  Dr Fujii and co-workers describe the evolution of Rf genes which produce proteins that block the action of the mitochondrial male-sterility inducing genes by binding to the RNA they produce.

This finding demonstrates a ‘civil war’ between the nucleus and the mitochondria over the determination of the sex of the plant that has been going on for millions of years.

Chief Investigator Professor Ian Small said: “Our analysis of the evolution of Rf genes not only strongly supports their role in sex determination, it also gives us clues as to exactly how they work.  The ability to silence destructive products in the cell has obvious possibilities in agricultural science and in medicine.  The potential to control the sex of a plant is also important in commercial crop breeding.”

Images available on request: ARC Centre of Excellence state of the art laboratories and scientists, close ups of plant sexual organs and flowers.