d-Lactate dehydrogenase as a marker gene allows positive selection of transgenic plants

d-Lactate negatively affects Arabidopsis thaliana seedling development in a concentration-dependent manner. At media d-lactate concentrations greater than 5–10 mM the development of wild-type plants is arrested shortly after germination whereas plants overexpressing the endogenous d-lactate dehydrogenase (d-LDH) detoxify d-lactate to pyruvate and survive. When the transgenic plants are further transferred to normal growth conditions they develop indistinguishably from the wild type. Thus, d-LDH was successfully established as a new marker in A. thaliana allowing selecting transgenic plants shortly after germination. The selection on d-lactate containing media adds a new optional marker system, which is especially useful if the simultaneous selection of multiple constructs is desired.

► A novel selection marker system based on the metabolism of d-lactate was developed.
► At high d-lactate concentrations wild-type development is arrested after germination.
► Plants overexpressing d-lactate dehydrogenase detoxify d-lactate and survive.
► d-LDH was established as marker in Arabidopsis thaliana allowing selection after germination.
► Selection on d-lactate adds a marker system as a good alternative to traditional ones.