Scientists Discover New Source of Maize Hybrid Vigor

Professor Steve Moose of the University of Illinois and his graduate student Wes Barber have discovered a new source of hybrid vigor in maize. Moose and Barber sampled small RNAs (sRNAs) from the seedling shoot and the developing ear of maize hybrids, the two tissues that grow rapidly and program growth, to investigate how the sRNA profiles of these hybrids differ from those of their parents.

They found that the differences are due mainly to hybrids inheriting distinct small interfering RNAs (siRNAs), a subset of sRNAs, from each parent. The siRNAs interfere with gene expression. They also found that hybridization does not create new siRNAs, but hybrids have a more complex siRNA population than their parents because they inherit distinct siRNAs from both parents. The differences in parental siRNAs originated primarily from repeats, which are the result of retrotransposon activity. Retrotransposons are elements that move around and amplify themselves within a genome.

Moose said that "We are not saying that genes are not important, but probably the way corn properties are altered in the hybrid situation is mediated by the small RNAs in addition to the genes." Moose and Barber hope that their work will provide more insight into deciding which inbred maize lines to cross. Moose added that "We don't want to alter how the plant grows, but if we can tweak it to do whatever it already does either faster or more, that could be an advantage."

The news release can be read at http://www.sciencedaily.com/releases/2012/06/120628164629.htm. The full paper is available at http://www.pnas.org/content/109/26/10444.full.