Aluminum tolerance of Arabidopsis thaliana under hydroponic and soil culture conditions

We compared the aluminum (Al) tolerance of three Arabidopsis thaliana ecoty pes [Columbia (Col-0), Wassilewskija (Ws), and Landsberg (Ler)] and an Al-t olerant line (Al-t) selected from Ler under both hydroponic and soil cultur e conditions. For the estimation of Al tolerance in primary roots in hydrop onic culture, the pH of the test solution containing 0-2.5 mu M Al was adju sted to 5.2 with HCl to minimize proton toxicity. Under these conditions, t he ecotype Ws was the most tolerant and Ler was the most sensitive to Al. T he line Al-t was more tolerant to Al than the parental ecotype of Ler. The Al tolerance was also determined in a typical highly acidic nonallophanic a ndosol (Kawatabi Kuroboku) with different concentrations of exchangeable Al adjusted with various amounts of CaCO3 and NaH2PO4. The diameter of the ro sette of each plant was measured as an indicator of Al tolerance under soil culture conditions. The order of Al tolerance under soil culture condition s among these ecotypes and the Al-t line was identical with that obtained u nder hydroponic culture conditions. Thus, we concluded that Al tolerance of A. thaliana in soils is strongly correlated with Al tolerance estimated un der hydroponic culture conditions.