Nitrogen fixation is a symbiotic process initiated by chemical signals from legumes that are recognized by soil bacteria. Here we show that some endocrine-disrupting chemicals (EDCs)^{1, 2, 3}, so called because of their effect on hormone-signalling pathways in animal cells, also interfere with the symbiotic signalling that leads to nitrogen fixation. Our results raise the possibility that these phytochemically activated pathways may have features in common with hormonal signalling in vertebrates, thereby extending the biological and ecological impact of EDCs.

1. Environmental Endocrinology Laboratory, Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana 70112, USA
2. Molecular and Cellular Biology Program, Tulane University, New Orleans, Louisiana 70112, USA
3. Department of Pharmacology, Tulane University Medical School, New Orleans, Louisiana 70112, USA

Correspondence to: John A. McLachlan^1,3 e-mail: Email: john.mclachlan@tulane.edu