Control of alien gene expression for aluminum tolerance in wheat

The expression of aluminum tolerance from rye (Secale cereale L.) when present in a wheat (Triticum aestivum L. em. Thell.) background has been observed to be much lower than that in rye itself. By crossing each of the ditelocentric lines of 'Chinese Spring' wheat with a tolerant rye, the effects of the presence or absence of each arm of wheat on the expression of rye aluminum tolerance could be established. Of 42 wheat chromosome arms, 18 affected the expression of rye aluminum tolerance. Tolerance was increased over that observed in the euploid wheat–rye hybrid when arms 4AL, 5AL, 6AL, 7BS, 7BL, and 3DS were absent. Tolerance was reduced when arms 2AL, 5AS, 6BS, 1DS, 1DL, 2DL, 4DL, 5DS, 5DL, 6DL, 7DS, and 7DL were absent. Thus, the control of aluminum tolerance expression from rye in a wheat background was evidently under the influence of genes located on a number of wheat chromosome arms, with a few arms tending to enhance expression and many others tending to reduce it. In fact, 5AS of 'Chinese Spring' enhances expression, while 5AL suppresses it. The D genome of bread wheat appears to have the most pronounced effect on the expression of rye aluminum tolerance.Key words: rye, activator genes, suppressor genes, alien manipulation.