A mechanistic understanding of soil N inhibition of biological N fixation (BNF) in high-BNF Saccharum spontaneum

Saccharum spontaneum, a progenitor of sugarcane, has large genotypic variation for BNF. In a BNF screening program we have identified high-BNF accessions of S. spontaneum. External application of synthetic N adversely affects BNF in sugarcane and many other plants including legumes such as soybean. However, we found that BNF in some S. spontaneum accessions are relatively less affected by external N, but little is known about the mechanistic basis of this phenomenon. Here we conducted an integrated molecular physiology study to gain insights into the mechanism underpinning BNF tolerance in S. spontaneum grown high external N supply.