Haploid induction by a maize <i>cenh3</i> null mutant

Abstract

The production of haploids is an important first step in creating many new plant varieties. One approach used in <i>Arabidopsis</i> involves crossing plants expressing different forms of centromeric histone H3 (CENP-A/CENH3) and subsequent loss of genome with weaker centromeres. However, the method has been ineffective in crop plants. Here, we describe a greatly simplified method based on crossing maize lines that are heterozygous for a <i>cenh3</i> null mutation. Crossing +/<i>cenh3</i> to wild-type plants in both directions yielded haploid progeny. Genome elimination was determined by the <i>cenh3</i> genotype of the gametophyte, suggesting that centromere failure is caused by CENH3 dilution during the postmeiotic cell divisions that precede gamete formation. The <i>cenh3</i> haploid inducer works as a vigorous hybrid and can be transferred to other lines in a single cross, making it versatile for a variety of applications.