Screening And Identification Of Arabidopsis Mutants With Selenite-Tolerance

Using the young seedlings of wild type of Arabidopsis thaliana as plant materials, the effects of selenite on plant growth were investigated by a serial of experiment. Ethyl methane-sulfonate (EMS)-mutagenized Arabidopsis M2 populations were screened for selenite-tolerance in high selenite medium using the germination method and the root-bending assay. The main results were as follows:The proper application of 1 mg/L selenite to Arabidopsis advanced its growth, increased the root length, hypocotyl length and fresh weight, while the growth of plant was restrained or even poisoned at excessive quantity of 10 mg/L selenite applied.Test showed that different parts of Arabidopsis had different Se absorption, when it was applied some selenium, the more selenite was contained in culture medium, the more selenium accumulated in plant and the Se content increased in the order of roots, leaves, stems. Also, GSH-Px and SOD activity was significiently strengthened as the concentration of the applied selenite was increased. And the activity of GSH-Px and SOD was in the order of roots, leaves, stems.When the plant grew in the medium of 10 mg/L selenite, the Se content of the roots, leaves and stems were all in the highest level of 183.52 μg/gDW, 163.35 μg/gDW and 127.62 μg/gDW. So was the activity of GSH-Px and SOD.Experiments of selenite applied were carried out and the results showed that the plant growth was postponed by using the root-bending assay and the gennination method. And we established a screened system to isolate the high selenite tolerant mutant of Arabidopsis, that was, root-bending assay on a medium containing selemte 40 mg/L in 6 d.Seventy-seven putative high selenite mutant were isolated from 1.06 million M2 seedlings. Among these mutants, twenty-two of them were screened from 0.25 million M2 seedlings by using the root-bending assay, and fifty-five of them were screened from 0.80 million M2 seedlings by the gennination method. Following experiment proved two of them maintained high selenite-tolerance in their M3 generations.Experiments of high selenite applied on the M4 generations of mutants named 15Aapproved its high selenite-tolerance. The more selenite was contained in the medium, the more selenium uptaked and accumulated by the high selenite tolerant mutant named 15A. The Se content of the mutant was 217.6 μg/gDW When it grew in the medium of 15 mg/L selenite. Compairing with the wild type, the mutant had higher Se content and stronger GSH-Px and SOD activity.