AUTHOR=Downie J. Allan , Kondorosi Eva 

TITLE=Why Should Nodule Cysteine-Rich (NCR) Peptides Be Absent From Nodules of Some Groups of Legumes but Essential for Symbiotic N-Fixation in Others?

JOURNAL=Frontiers in Agronomy

VOLUME=3

YEAR=2021

URL=https://www.frontiersin.org/journals/agronomy/articles/10.3389/fagro.2021.654576

DOI=10.3389/fagro.2021.654576

ISSN=2673-3218

ABSTRACT=<p>In nitrogen-fixing nodules of legumes such as pea <italic>(Pisum)</italic> and <italic>Medicago</italic> spp. the plant induces terminal differentiation in the rhizobial endosymbionts by targeting nodule-specific cysteine-rich defensin-like peptides into the bacteria. However, in nodules of other legumes such as soybean and <italic>Lotus</italic> spp. terminal bacterial differentiation does not occur; these legumes lack genes encoding equivalent peptides controlling rhizobial development. Here, we review the effects of some of these peptides on rhizobia and address the question as to how and why such peptides may have evolved to enslave rhizobia and become essential for nitrogen fixation in some clades of legumes but not in others.</p>