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Zea mays, known as maize or corn, is a plant in the grass family (Poaceae) cultivated for its seeds which are eaten as a human staple crop and used in animal feed. Many varieties are grown and used to study genetics, development, domestication and biotechnology.
In this Review, the author discusses current knowledge on the paramutations that occur in maize and contrasts these behaviours with potentially parallel examples in metazoans. He highlights the key role of small RNAs (sRNAs) in diverse paramutation mechanisms across eukaryotes and considers the evolutionary importance of these regulatory systems.
Jinsheng Lai and colleagues report the resequencing of 278 inbred maize lines and perform a genome-wide analysis of genetic changes during modern breeding. Using SNP imputation, the authors also perform a genome-wide association study for cob color, silk color and date to anthesis. The authors identified association signals with significant P values near known targets.
Albrecht Melchinger and colleagues report a complementary approach to phenotype-based screening for hybrid maize. The new approach accurately predicts the combining abilities of agronomical traits based on genomic and metabolomic information comprising 56,110 SNPs and 130 metabolite measurements.
The nucleotide diversity present in maize exceeds that in humans by an order of magnitude, and it has been challenging to characterize the high levels of diversity in this important crop. Doreen Ware and colleagues have identified 55 million SNPs in 103 domesticated and pre-domestication Zea mays varieties, as well as in a representative from the sister genus Tripsacum.
Three new studies report large-scale resequencing and comparative genomic analysis of diverse maize varieties. The authors conducted a comprehensive characterization of sequence variation in maize genomes and identified signals of selection in maize domestication and breeding.