The significance of organic-anion exudation for the aluminum resistance of primary triticale derived from wheat and rye parents differing in aluminum resistance

Eight primary octoploid triticale genotypes (xTriticosecaleWittmack) derived from four wheat cultivars (Triticum, aestivum L.) and two rye inbred lines (Secale cereale L.) differing in aluminum (Al) resistance were investigated with respect to their response to Al supply. Aluminum-induced inhibition of root elongation (48 h, 25 mu M Al supply), callose formation, and the accumulation of Al in root tips (4 h, 25 mu M Al supply) were used as parameters to assess Al resistance. Using these parameters, the existing information on Al resistance of the wheat and rye cultivars was generally confirmed. The triticale cultivars showed a wide range of Al resistance amongst the Al-sensitive wheat and the Al-resistant rye cultivars. The rye parents and the Al-resistant wheat parent Carazinho were characterized by Al-induced exudation particularly of citrate but also of malate from whole root systems of 14 d old seedlings (8 h, 50 mu M Al supply). Regression analysis revealed that the degree of Al resistance of the triticale genotypes was closely related to the Al-induced citrate exudation, which was mainly controlled by the Al resistance of the wheat parent.