Inheritance of polyembryony in flax (Linum usitatissimum)
The inheritance of polyembryony (haploid–diploid twin seedlings) in the cross between Linum usitatissimum L. cv. Avantgarde (zero twinning) and cv. Rocket 4 (6.6% twins) was examined. It was concluded that the production of polyembryonic seeds is controlled mainly by additive gene action, with a realized narrow-sense heritability of 0.8. The frequency of twinning in the F2 generation displayed substantial transgressive segregation, ranging from zero to 32.0%. It was considered that such transgression could be due to either the presence of residual heterogeneity for twinning alleles in cv. Rocket 4, or the existence of a genetic system suppressing the expression of twinning alleles in cv. Avantgarde. The occurrence of a genotype producing haploid plants from more than 30% of its seeds should enable the efficiency of doubled-haploid line production to be greatly improved, and also lead to a better understanding of the embryological origins of the haploid component of polyembryonic seeds.