Inheritance of aluminum tolerance in the wheat cultivar Toropi and new findings about the introduction of this trait into the Brazilian wheat germplasm

Aluminum (Al) is the most abundant metal in the earth's crust, and in acidic soils it dissolves into the phytotoxic form Al3+. Analysis of the inheritance of aluminum tolerance in a donor genotype is an important step in the development of new cultivars adapted to acidic soils. The Brazilian wheat cultivars BH1146 and Carazinho have been important donors of aluminum tolerance genes in wheat breeding programs around the world. This trait is under the control of two main genes, TaALMT1 and TaMATE1B. Interestingly, both cultivars have both of these genes, but different alleles. Lineages developed in Brazil from local landraces gave rise to the cultivars BH1146 and Carazinho, as well as other genotypes among which the cultivar Toropi is highlighted herein because of its excellent performance in acidic soils. It is not known if the genes and alleles responsible for aluminum tolerance in Toropi are the same as those carried by BH1146 and Carazinho. We analyzed the recombinant inbred lines (RILs) from Toropi × Anahuac (an Al-susceptible cultivar) and showed that aluminum tolerance in Toropi was controlled by one gene with major effects on the phenotype, although other gene(s) with minor effects also affected this trait. The analysis of RILs from Toropi × BH1146 showed that this major gene was different from the one carried by BH1146. The genealogy and molecular analyses of the TaALMT1 and TaMATE1B genes of the Al-tolerant Brazilian wheat cultivars allowed us to establish that Toropi has the same allele of the TaMATE1B gene as Carazinho, but probably originating from a different source.