Heritable variation in the ability to produce haploid embryos via pollination with maize and embryo rescue in durum wheat

Pollination with maize is commonly used to produce fertile doubled haploid plants in durum wheat. However, the genetic basis for the ability of parental lines to produce haploid seedlings is not well documented. A maximum likelihood procedure was used to analyse the response of 15 F-1, from a half diallel design involving six inbred lines, and to document rigorously the existence of heritable variation for haploid embryo production. Cross-effects and "general combining abilities" (GCA) were computed to estimate the ability to produce swollen ovaries and viable embryos. On average, the ovary swelling production was 56% and 11% of emasculated flowers produced a viable embryo. For both variables, cross-effect was significant. Based on GCA estimations, the 6 parental lines could be distributed in 3 different groups. The GCA values explained respectively 69% and 79% of the cross-effect for each variable. On the whole, ovary swelling was a poor predictor of embryo formation. No significant correlation was found between the per se values of the 6 parental lines and their GCA.