AUTHOR=Ma Yanlin , Chen Rujin 

TITLE=Nitrogen and Phosphorus Signaling and Transport During Legume–Rhizobium Symbiosis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.683601

DOI=10.3389/fpls.2021.683601

ISSN=1664-462X

ABSTRACT=<p>Nitrogen (N) and phosphorus (P) are the two predominant mineral elements, which are not only essential for plant growth and development in general but also play a key role in symbiotic N fixation in legumes. Legume plants have evolved complex signaling networks to respond to both external and internal levels of these macronutrients to optimize symbiotic N fixation in nodules. Inorganic phosphate (Pi) and nitrate (NO<sub>3</sub><sup>−</sup>) are the two major forms of P and N elements utilized by plants, respectively. Pi starvation and NO<sub>3</sub><sup>−</sup> application both reduce symbiotic N fixation <italic>via</italic> similar changes in the nodule gene expression and invoke local and long-distance, systemic responses, of which N-compound feedback regulation of rhizobial nitrogenase activity appears to operate under both conditions. Most of the N and P signaling and transport processes have been investigated in model organisms, such as <italic>Medicago truncatula</italic>, <italic>Lotus japonicus</italic>, <italic>Glycine max</italic>, <italic>Phaseolus vulgaris</italic>, <italic>Arabidopsis thaliana</italic>, <italic>Oryza sativa</italic>, etc. We attempted to discuss some of these processes wherever appropriate, to serve as references for a better understanding of the N and P signaling and transport during symbiosis.</p>