Assessment and Improvement of Wheat Microspore derived Embryo Induction and Regeneration

In this study we present an efficient protocol for the production of embryos in isolated wheat microspore culture and discuss parameters determining the efficiency of embryo induction and green plant regeneration. Microspores were isolated from the spring wheat genotypes DH83Z118.32 and DHBW3 showing high and low androgenetic response, respectively. The washing (WM) and induction/culture medium (AMC) were optimised and led to an average embryo yield of 1350 embryos per 105 microspores with DH83Z118.32. One single culture dish yielding 7250 embryos per 105 microspores demonstrated that the androgenetic potential of this genotype is even higher. With DHBW3 an average of 82 embryos per 105 microspores was achieved. We developed a non-destructive UV fluorescence image processing system that revealed a correlation between size parameters of microspore populations and their embryo yield. For DH83Z118.32 we found the ability of embryos to regenerate green plants (embryo quality) to be strongly determined by embryo age and size. The highest yield of regenerated green plants was obtained when large embryos (\s>4 mm) were transferred to regeneration medium 25 days after microspore isolation. The formation of albinos was negatively correlated with the embryo size. The early assessment of microspore size and embryo quality combined with optimised culture methods demonstrated that the potential of wheat haploid induction by isolated microspore culture is not yet fully exploited.