Essentiality of Boron for Symbiotic Nitrogen Fixation in Legumes and Actinorhizal Plants

Abstract

Boron (B) is a micronutrient essential for the development of higher plants, diatoms and some species of algae. However, it is apparently not required by fungi and bacteria (Blevins and Lukaszewski 1998). An exception are the heterocystous cyanobacteria (blue-green algae) which require B when growing under N2-fixing conditions for the stabilisation of the envelope which controls the access of oxygen to the heterocyst (Bonilla et al. 1990, García-González et al. 1991).