Differences in in vitro plant regeneration ability among four Arabidopsis thaliana ecotypes

The Arabidopsis ecotypes Columbia (Col), Landsberg erecta (Ler), Cape Verde Island (Cvi) and Wassilewskija (WS) have been tested for their regeneratio n, response in vitro. A characteristic morphology of leaf-derived calluses has been found for each ecotype. Differences in regeneration ability have b een detected depending on the plant strain, the explant source and on the c ulture medium composition. in CIR/SIR media, which contain 0.5 mg l(-1) (2. 26 muM) of 2,4-dichlorophenoxyacetic acid (2,4-D) and glucose, root explant s from the four ecotypes are able to reach a considerable regeneration leve l, while leaf explants do not regenerate beyond a basal level (5% approxima tely). In CIH/SIH media,,which contain 2.2 mg 1(-1), (9.95 muM) of 2,4-D an d sucrose, leaf explants from all the ecotypes, with the exception of Col, are able to. regenerate, but they do it at variable levels, (Ler 55.750/a, WS 75.09%, and Cvi 27.53% as regeneration rates). With these media all root explants are able to, regenerate, but again the four ecotypes show differe nt rates (Col 27.70%, Ler 57.25%, WS 98.54%, and Cvi 42.25%). The variation of the different medium components affects differentially the regeneration ability of the four ecotypes depending also on, the kind of explant. Thus, when the 2,4-D concentration is raised WS duplicates its regeneration rate in both leaf and root explants. Changing glucose for sucrose in CIR/SIR me dia diminishes to the basal level the regeneration of Cvi root explants, wh ile the CIH/SIH salts and vitamin concentration permit the regeneration of leaf explants from all the ecotypes except Col. The genes responsible for t hose observed differences in regeneration ability could be identified and m apped by analyzing the in vitro regeneration behavior of the recombinant in bred lines (RIL's), obtained by, crossing these ecotypes.