Highly efficient doubled-haploid production in wheat (Triticum aestivum L.) via induced microspore embryogenesis

An efficient doubled-haploid production technology that induces homozygosity can greatly reduce the time and cost of cultivar development. Low efficiency of doubled-haploid production preciously has limited exploitation of this method for crop improvement. This study aimed to develop a more efficient and effective isolated microspore culture system for generating doubled-haploid wheat (Triticum aestivum L.) plants. We report here the development and testing of a new chemical formulation for its efficiency to induce microspore embryogenesis, and the development of a system for double haploid production, in which the induction of embryogenesis in microspores was followed by isolating embryogenic microspores, and culturing them under optimized growth conditions to produce high embryoid yields. Up to 50% of the total treated microspores in the whole spike were converted from their preprogrammed gametophytic to a sporophytic pathway by a chemical inducer formulation consisting of 0.1 g L-1 of 2-hydroxnicotinic acid, 10(-6) mol L (1)2,4-dichlorophenoxyacetic acid, and 10(-6) mol L-1 6-benzylaminopurine. The isolated embryogenic microspores were cocultivated with live wheat ovaries in a liquid NPB 99 media with an osmolality of about 300 mOsmol kg(-1) H2O, resulting in the regeneration of 50 to 5500 green plants per single spike of eight wheat genotypes. The high efficiency and simplicity make the system practical for biological research and for accelerating cultivar development in wheat breeding programs.