Biologists undress the genetic hierarchy in plant sperm cell formation

© Jerome Twell; Genetic circuit directing the production of twin sperm in each pollen grain - in which the master control gene DUO1 switches on the DAZ1 and DAZ2 proteins to control cell division to allow twin sperm production to proceed

A team from the Department of Biology led by Professor David Twell has solved a mystery surrounding how plants have sex - and have discovered a pair of proteins made by flowering plants that are vital for the production of the sperm present within individual grains of pollen.

The study by researchers in the Twell Laboratory which has been published in the prestigious academic journal The Plant Cell, has found a pair of genes called DAZ1 and DAZ2 that are essential for making twin sperm cells. Plants with mutated versions of DAZ1 and DAZ2 produce pollen grains with a single sperm that is unable to fertilize.

The research shows that DAZ1 and DAZ2 are controlled by the protein DUO1 that acts as a ‘master switch’ - so that DUO1 and the DAZ1/DAZ2 genes work in tandem to control a gene network that ensures a pair of fertile sperm is made inside each pollen grain.

Interestingly, DAZ1 and DAZ2 perform their role by cooperating with a well-known ‘repressor’ protein called TOPLESS that acts as a brake on unwanted gene activity that would otherwise halt sperm and seed production. Although TOPLESS has many roles in plants it has not previously been linked sperm production.

This new knowledge has the potential to be applied in the development of new plant breeding techniques to prevent the unwanted passing of genes – or ‘horizontal gene transfer’ - between crops or from crops to wild species and could generate new ways of monitoring the effects of, environmental stresses on the reproductive process. In future such information may become increasingly important as we strive to breed superior crops that maintain yield in a changing climate.

The study, ‘An EAR-Dependent Regulatory Module Promotes Male Germ Cell Division and Sperm Fertility in Arabidopsis’, is published in the May 2014 issue of The Plant Cell and can be read here.