Linkage of RFLP markers to an aluminum tolerance gene in wheat

More than 20% of the world's agricultural land may contain acid soil. Aluminum toxicity becomes a serious growth limiting factor in many plant species when the soil pH is lower than 5.5. Wheat (Triticum aestivum L.) genotypes differ widely in tolerance to excess Al, and breeding of more tolerant genotypes is a priority in many affected regions. Our objectives were to confirm the number of genes for Al tolerance and determine their chromosomal arm location in the Brazilian wheat cv. BH 1146 and to identify DNA markers linked to Al tolerance gene(s). A population of recombinant inbred lines, developed by singles descent from the cross of BH 1146 X 'Anahuac', was screened for Al tolerance with two methods in hydroponic nutrient solution. Both methods showed a bimodal distribution for Al tolerance, consistent with single gene inheritance. Eighty-three low-copy DNA clones were used to screen for polymorphism between the parents. Clone bcd1230 detected a restriction fragment that is located 1.1 centiMorgans from this gene on Chromosome 4DL and explained 85% of the phenotypic variation in Al tolerance. We propose the symbol Alt(BH) to designate the major gene for Al tolerance located on 4DL. This RFLP marker can aid the transfer of this gene into sensitive germplasms.