Plant scientists have known for some time that genes from the maternal plant control seed development, but they have not known quite how.
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.
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.
Funded by Biotechnology and Biological Sciences Research Council
