Assessment and improvement of wheat microspore derived embryo induction and regeneration

In this study we present an efficient protocol for the production of embryo s in isolated wheat microspore culture and discuss parameters determining t he efficiency of embryo induction and green plant regeneration. Microspores were isolated from the spring wheat genotypes DH83Z118.32 and DHBW3 showin g high and low androgenetic response, respectively The washing (WM) and ind uction/culture medium (AMC) were optimised and led to an average embryo yie ld of 1350 embryos per 10(5) microspores with DH83Z118.32. One single cultu re dish yielding 7250 embryos per 105 microspores demonstrated that the and rogenetic potential of this genotype is even higher. With DHBW3 an average of 82 embryos per 10(5) microspores was achieved. We developed a non-destru ctive UV fluorescence image processing system that revealed a correlation b etween size parameters of microspore populations and their embryo yield. Fo r DH83Z118.32 we found the ability of embryos to regenerate green plants (e mbryo quality) to be strongly determined by embryo age and size. The highes t yield of regenerated green plants was obtained when large embryos (>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 op timised culture methods demonstrated that the potential of wheat haploid in duction by isolated microspore culture is not yet fully exploited.