Tracing of 2n egg occurrence in perennial ryegrass (Lolium perenne L.) using interploidy crosses

Several genotypes of Lolium perenne (2n = 2x = 14) were screened for the production of 2n eggs. In each cross a diploid genotype, used as female parent, was pollinated with a tetraploid genotype. All interploidy crosses were made in isolation cages. Flow cytometrical analysis of the progeny of 154 diploid plants revealed 28 tetraploid descendants. These offspring plants were harvested on 15 different diploid mother plants. Amplified Fragment Length Polymorphism (AFLP) markers were used to check the parenthood of these tetraploids. Two seedlings died, the remaining plants could, after AFLP fingerprinting, be identified as meiotic tetraploids. The results obtained allowed to conclude that the tetraploid progeny plants harvested on 15 diploid mother plants were the result of the fertilisation of an unreduced egg by a reduced pollen grain of the tetraploid plant.