Scientists from the University of Kentucky led by Professor Hongyan Zhu have
discovered a more efficient way for legumes to fix
nitrogen. Zhu and his team found two antimicrobial peptides in the legume
Medicago truncatula that kill certain rhizobial bacteria as nitrogen
fixation begins. M. truncatula is closely related to
load/biotech-crop-annual-update-alfalfa-2016.pdf> alfalfa, a forage legume.
Zhu believes that the antimicrobial proteins originally functioned to kill
bacteria as they entered the plant, but have evolved to manipulate certain
bacteria to start the nitrogen fixation process. Bacteria that do not
tolerate the peptides die almost immediately. "This finding offers
scientists a strategy to improve nitrogen fixation in legumes by selecting
or manipulating these genes to accept more bacteria. This could potentially
allow legumes to fix more nitrogen," Zhu said.