Imprinting meets genomics: new insights and new challenges

Until recently, only a handful of imprinted genes, or genes with parent-of-origin dependent expression patterns, were known in plants. Study of these genes yielded key insights into mechanisms of monoallelic expression and imprinted gene function. The recent application of high throughput sequencing to the study of imprinting has confirmed that many previous findings are relevant on a genome-wide scale. The catalogue of imprinted genes in monocots and dicots now includes a large number of transcription factors, chromatin related genes, and metabolic or hormone biosynthesis enzymes. Interpretation of allele specific expression data remains a challenge, with careful validation of candidate imprinted genes necessary.