Twinned microspore-derived embryos of canola (Brassica napus L.) are genetically identical

Microspore culture is used extensively in several crop species to generate diverse populations of homozygous, doubled haploid lines for breeding and genetic analyses. In our canola (Brassica napus L.) doubled haploid breeding programme we regularly observe conjoined microspore-derived embryos, most commonly twins, joined either at the base of the hypocotyl or along the length of the hypocotyl axis. The aim of this study was to determine if twinned embryos were genetically identical or non-identical in order to gauge their value for breeding and linkage analysis. Microsatellite marker fingerprinting of 12 pairs of twinned embryos produced by microspore culture of heterozygous F-1 lines revealed that pairs of twins were genetically identical. Based on this finding, we recommend breeders and geneticists using microspore culture technology to retain only one embryo from each pair of twinned embryos.