A Novel Gene Silencing Mechanism in Corn

Researchers at the University of Delaware, in collaboration with scientists from the South Dakota State University and University of Arizona identified a novel gene silencing mechanism in corn that helps protect the crop from mutation-causing viruses and jumping genes. The discovery was made by comparing the impact of inactivating a gene that occurs in both corn and in the model Arabidopsis.

Scientists from the University of Delaware had previously studied Arabidopsis mutants with non-functional RNA-dependent RNA polymerase 2 (RDR2) gene. RDR2 encodes an enzyme that allows plants to produce a group of small RNAs, which in turn act to protect the integrity of genes on the chromosome. University of Arizona researchers, in a different study, identified a gene in maize equivalent to the RDR2 of Arabidopsis. Because the RDR2 and MOP1 genes should both produce the “protective” set of small RNAs, the research groups decided to collaborate to see if the small RNAs in corn behave the same way they do in Arabidopsis.

The researchers found that there are lots more RNAs of an unusual class known as “small interfering RNAs (siRNAs)” in corn than there are in Arabidopsis. This class of RNAs mainly functions to repress repetitive sequences, including jumping genes. Since there are more protective small RNAs in maize than in Arabidopsis, the scientists suspect that there are additional genes other than MOP1 that produce the siRNAs.

Read the full article at http://www.udel.edu/udaily/2009/oct/corn103008.html