Aluminum tolerance genes on the short arm of chromosome 3R are linked to organic acid release in triticale

Triticale, a hybrid between wheat and rye, shows a high degree of Al tolera nce that is inherited from rye, but the mechanisms of high Al tolerance in both rye and triticale are unknown. We found that the short arm of chromoso me 3R carries genes necessary for Al tolerance in triticale (x Triticosecal e Wittmark cv Currency). Detailed comparative studies with a 3DS.3RL transl ocation line (ST22) and a non-substitution line (ST2) were conducted. Root elongation was similarly inhibited by Al in ST2 and ST22 during the first 1 2 h of Al treatment, but more strongly in ST22 than in ST2 at 18 h and ther eafter. The root inhibition induced by other metals (Cu, Cd, and La) was si milar between ST2 and ST22, suggesting that the action of the genes for Al tolerance on the short arm of triticale chromosome 3R is highly specific to Al. A 2-fold larger amount of malate and citrate was released from the roo ts of STZ than From ST22 at 12 and 18 h after Al treatment, respectively. T he marked lag phase in the inhibition of root elongation and the release of organic acids implies that the expression of genes on the short arm of tri ticale chromosome 38 is induced by Al, and that these genes are necessary f or the release of organic acids.