Scientists at the University of Oxford have paved the way for bigger
and better quality maize crops by identifying the genetic processes that
determine seed development.
Plant scientists have known for some time that genes from the maternal
plant control seed development, but they have not known quite how. The
Oxford research, supported by the Biotechnology & Biological Sciences
Research Council (BBSRC) and highlighted in the new issue of BBSRC Business,
has found at least part of the answer.

Working in collaboration with researchers in Germany and France,
Professor Hugh Dickinson's team found that only the maternal copy of a key
gene responsible for delivering nutrients is active. The copy derived from
the paternal plant is switched off. This gene encodes a potential signalling
molecule found in the endosperm - a placenta-like layer that nourishes the
developing grain, which is involved in 'calling' for nutrients from the
mother plant, and so triggers an increased flow of resources. Similar
mechanisms can almost certainly be expected in other cereals, and with
cereal grain being a staple food across the world, the potential to harness
this science to improve yields is clear.

Prof. Dickinson explains: "By understanding the complex level of gene
control in the developing grain, we have opened up opportunities in
improving crop yield.

"The knowledge and molecular tools needed to harness these natural
genetic processes are now available to plant breeders and could help them
improve commercial varieties further. For example, they can better
understand how to successfully cross-breed to produce higher quality crops.
The cereal grain is a staple food of the world's population: with the
changing climate and growing population, the need for sustainable
agriculture is increasingly pressing."

The mechanism used to switch off paternal genes ensures supremacy of
maternally-derived genes. This process is known as 'imprinting' and is
achieved mainly through 'methylation' - a naturally occurring chemical
change in the DNA. A very similar mechanism takes place in animal embryos.
However, unlike the animal imprinting systems where genes are often grouped
in the chromosomal DNA, in maize imprinted genes are 'solitary' and
independently regulated.
[www.innovations-report.de]