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For more than a century, plant geneticists have been studying maize as a model system to understand the rules governing the inheritance of traits. Now, a team of researchers has unveiled a previously unknown mechanism that triggers gene silencing in corn. Gene silencing turns off genetic traits, an important consideration for plant breeders who depend on the faithful inheritance of traits from one generation to the next.
The team showed that silencing the corn pericarp color 1 gene -- regulator of the kernels' outer layer color and the cob color -- can have two "overlapping" epigenetic components: RNA dependent DNA methylation (RdDM) and non-RNA dependent DNA methylation (non-RdDM). Small RNAs -- molecules essential in regulation and expression of genes -- can mediate methylation of DNA strands and shut down transcription activity, thereby playing a role in silencing inherited genes or transgenes introduced to produce desirable crop traits. A better understanding of how gene-silencing mechanisms cause the disappearance of desired traits has long been needed. It can be disastrous for a farmer to buy seeds that do not behave in the grow-out the way they were promised by the producer.Image credit: Surinder Chopra/Penn State
