A team of researchers has uncovered a previously unknown mechanism that triggers gene silencing in corn. Gene silencing turns off genetic traits, and plant breeders consider it as the key on trait inheritance from one generation to the next.

Lead researcher Surinder Chopra, professor of maize genetics in the College of Agricultural Sciences at Penn State and his team showed that silencing the corn pericarp color 1 gene can have two "overlapping" epigenetic components — RNA dependent DNA methylation (RdDM) and non-RNA dependent DNA methylation (non-RdDM).

The pericarp color 1 gene regulates the accumulation of brick-red flavonoid pigments called phlobaphenes. The pattern of pigmentation on the corn kernel pericarp and "glumes" depends upon the expression of this gene. Some examples of these patterns are: white kernels, red cob; red kernels, red cob; variegated kernels, variegated cob; red kernels, white cob; and white kernels, white cob.

Chopra said that the study showed the involvement of both small RNA-dependent and small RNA-independent mechanisms for gene suppression. He added that the study revealed the additional layer of gene regulation by small RNAs, and improved their understanding of how gene expression is regulated specifically in one tissue but not in the other.

For details, read Penn State News.

Figure: Gene silencing can cause genes to not express, losing those traits in the final cob. The pattern of pigmentation on the corn kernels and the cobs depends upon the position of the pericarp color 1 gene, and whether it is silenced. Image: Surinder Chopra, Penn State