A study of transcript profiling of soybean roots during nitrogen fixing symbiosis

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Nodulation is a symbiotic association between a host plant and its bacterium. The result of this interaction is the formation of a novel organ, the nodule that is able to fix atmospheric nitrogen with very high efficiency, providing a nitrogen source for plant growth. The association between Bradyrhizobium japonicum and soybean, a plant of high agronomic importance, leads to the establishment of the nitrogen fixing symbiosis. The soybean gene GmNARK (Glycine max Nodule Autoregulation Receptor Kinase) regulates the number of nodules. The supernodulating NARK mutant (SS2-2) was found to have a single nucleotide polymorphism (SNP) in comparison to the wild-type allele in the cultivar Sinpaldalkong2. Transversion of A to T within this gene results in a change of lysine to a stop codon; thus, terminating its translation in the mutant. The mutant (SS2-2) was used to identify genes having a critical role in this symbiosis. For that purpose, RNA extracted from 4, 8 and 16 day old roots inoculated or not with B. japonicum.