Studies On Dedifferentiation Of Mature Wheat Embryos And Plant Regeneration

In order to study the feasibility of wheat mature embryos as explants for callus induction and plant regeneration, 8 different genotypes common winter wheat (Triticum aestivum) mature embryos were used under different culturing conditions of endosperm-supported (ES, aseptically moved slightly but not set free) or endosperm-no-supported (ENS, mature embryos were excised from seeds and separated from endosperm) and dichlorophenoxyacetic acid (2,4-D) concentrations (2 mg/l or 8 mg/l). During culturing, the enzymatic activities of PM H+-ATPase and oxalate oxidase, two key enzymes in callus induction and plant regeneration, were dectected and the relationships between enzymatic activities and capacities of plant regeneration were analyzed. To study the roles of PM H~+-ATPase in dedifferentiation and redifferentiation further, PM H~+-ATPase gene was cloned from wheat calli, the nucleotide sequence of PM H~+-ATPase in wheat was aligned with that from other different plants, the expression of PM H~+-ATPase gene during culture process was analyzed by Northern Blot. Finally, the molecular three-dimensional structure and functions of the emzye were predicted. The main results were as follows:1) In ENS culturing condition, callus induction rates and differentiation rates were 82.7% and 19.1 % in lower 2,4-D concentration(2 mg/l) culturing, respectively. In higher 2,4-D concentration(8 mg/l) culturing callus induction rates and differentiation rates were 82.1 % and 11.2%. The lower 2, 4-D concentrations(2 mg/l) could improve callus differentiation and regeneration capacity. In ES culturing condition, callus had low callus induction efficiency (53.2%), but high plant regeneration efficiency (65.8%). The results indicated that, comparing with ENS culturing condition ES could dramatically enhanced plant regeneration rates.2) Correlation analysis between different characters in mature embryos culturing under different treatments showed that there were some or significant negative correlations between callus induction efficiency and green spot differentiation, callus induction efficiency and regeneration efficiency, i.e. the lower callus induction...