Expression of maize genes on a specific chromosome in the presence of a foreign genome.

Abstract

Oat-maize addition (OMA) lines are derived from oat x maize sexual hybrids in which individual maize chromosomes have been retained in embryo-rescued plants containing a full complement of oat chromosomes. The maize Affymetrix microarray was used to analyze transcripts from three independently derived OMA lines containing chromosome 5 from the B73 maize inbred line in order to assess the prevalence of maize gene expression in an alien background. Despite the lack of gross morphological changes, we found that 26% of the maize genes that are normally expressed in maize seedlings are also expressed in OMA seedlings. All three OMA lines show very similar gene expression patterns. While there was evidence for expression for many of the maize genes on chromosome 5, there were also numerous chromosome 5 genes that are normally expressed in maize but expression was not detected in OMA lines. The expression, or lack thereof, of a maize chromosome 5 gene was not correlated with chromosomal position, gene annotation or DNA methylation. Although there is a correlation between expression levels of the maize chromosome 5 genes expressed in OMA and maize, the expression levels are generally lower in the OMA background. The basis for maize gene expression in the maize donor but not in the OMA lines likely reflects whether maize genes can be efficiently controlled by oat transcriptional machinery.