Detlef Weigel (born 1961 in Lower Saxony, Germany) is a German American[1] scientist working at the interface of developmental and evolutionary biology.

Weigel began to work with plants during his postdoctoral research with Elliot M. Meyerowitz at Caltech, where he cloned the floral regulator LEAFY from Arabidopsis thaliana.

Together with Ove Nilsson, he demonstrated that transfer of the LEAFY gene from Arabidopsis thaliana to aspen trees was sufficient to reduce the time to flowering from years to months.

Apart from work on genetic variation in environment-dependent developmental processes, his group is known for the generation of extensive genomic resources, such as the first haplotype map for a non-mammalian species.

They could show that in certain hybrid offspring, specific gene products contributed by one of the parents may be inappropriately recognized as foreign and pathogenic, and thus trigger pervasive cell death throughout the plant.