What are low-accumulating genotypes?

What are low-accumulating genotypes? And how does it differ from high-accumulating genotypes?

Certain organisms and strains of organisms can accumulate certain substances, such as Cd (a toxic heavy metal). If they accumulate those compounds more rapidly and in higher amounts, the organisms can be said to be high-"substance" accumulating organisms, e.g high-Cd accumulating organisms. The genotype which causes being a high-Cd accumulating organism can be described as a high-"x" accumulating genotype, like in this paper. A high-accumulating genotype without reference to a certain substance doesn't make much sense. These genotypic predispositions to accumulation are often used with toxic heavy metals like cadmium and arsenic which persist in the body.

As another "substance" example, high-"x" accumulating organisms is also used in the description of high-plaque accumulating organisms, e.g in this paper.