Aluminum-stress response in oat genotypes with monogenic tolerance

Aluminum (Al) toxicity is one of the limiting factors in agricultural productivity on acid soils. The oat genotypes UFRGS17 and UPF91Al100-1-4 have been developed through different breeding programs and are classified as Al-tolerant. Genetic analysis indicated that the Al tolerance in each genotype is conferred by one gene. Pyramiding Al tolerance genes may increase the tolerance level. The objectives of this study were to determine whether the Al-tolerance observed in both genotypes is conferred by different genes and to investigate the tolerance mechanisms. The aluminum tolerance of the F2 population derived from the UFRGS17 × UPF91Al100-1-4 cross was estimated by using the regrowth of the primary root, and the tolerance was compared to the parental frequency distribution. The tolerance mechanism was investigated in seedlings after Al exposure for seven days. Al accumulation in the root apex was visualized, and the activity of antioxidant enzymes, the content of non-protein thiol groups and the concentrations of ascorbic acid, superoxide and H2O2 in the root apex, the differentiated root region and the shoots were measured. Al tolerance in UFRGS17 and UPF91Al100-1-4 is conferred by the same gene. A diverse pattern of Al accumulation was obtained for the genotypes, suggesting that the external detoxification is not the main mechanism of tolerance. The tolerant genotypes were able to manage the oxidative stress caused by Al on the other hand the sensitive genotype showed higher oxidative stress and lipid oxidation. The relative importance of each antioxidant component could not be established because different responses were observed between the Al-tolerant genotypes. It is possible that the Al-tolerance gene codifies an upstream component, such as a transcription factor, which once induced by Al, ends up activating, among other pathways, the antioxidative system.

► Aluminum tolerance in UFRGS17 and UPF91Al100-1-4 oat genotypes is conferred by the same gene.
► A diverse pattern of aluminum accumulation was obtained for the tolerant genotypes.
► The tolerant oat genotypes were able to manage the oxidative stress caused by aluminum.
► The major gene conferring tolerance to aluminum is not related to external detoxification.