Genetic control of aluminium tolerance in rye (Secale cereale L.)

Aluminium (Al) tolerance in roots of two cultivars (''Ailes'' and ''JNK'') and two inbred lines (''Riodeva'' and ''Pool'') of rye was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line ''Riodeva'' was sensitive (non-telerant) at a concentration of 150 mu M, whereas the ''Ailes'' cultivar showed the highest level of Al tolerance at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F(1)s, F(2)s and backcrosses between plants of ''Ailes'' and ''Riodeva'' were also studied. The segregation ratios obtained for aluminium tolerance in the F(2)s analysed were 3:1 and 15:1 (tolerant:non-tolerant) while in backcrosses they were 1.1 and 3.1. These results indicated that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Acol and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome.