Genetic correlation between arsenate tolerance and the rate of influx of arsenate and phosphate in Holcus lanatus L.

Arsenate tolerant genotypes of Holcus lanatus L. possess an altered phosphate and arsenate uptake system such that the rate of influx of arsenate and phosphate is much lower in tolerant plants than in non-tolerant plants, especially at low arsenate concentrations. The rate of influx of both arsenate and phosphate was studied in segregating and non-segregating families derived from crosses between mine and non-mine plants. In non-segregating families, all progeny had low uptake of arsenate and phosphate; in segregating families non-tolerant plants had higher rates of arsenate and phosphate uptake than the tolerant plants. The altered phosphate (and arsenate) uptake system was genetically correlated to arsenate tolerance. The two characters may represent the pleiotropic effects of the same genes, or they may show very tight genetic linkage. In the absence of recombinants, the former explanation is preferred. These results are further evidence that reduced arsenate uptake is a mechanism of arsenate tolerance in H. lanatus.