Processing of NODULE INCEPTION controls transition to nitrogen fixation in root nodules

To understand the role of Medicago truncatula NODULE INCEPTION (MtNIN) in nodule development, we analyzed the transcriptome of roots ectopically overexpressing NIN, nodules of weak mutant allele nin-16, and nodules of dnf1-2 mutant. To generate NIN and GFP over-expression plants, both NIN and GFP were cloned into level 2 binary vectors under the control of the L. japonicus UBIQUITIN promoter and transformed using A. rhizogenes. The transcriptional response to NIN overexpression (NINox) in 3-week old hairy roots was compared to control roots expressing GFP. Nodules of A17, dnf1-2, R108 and nin-16 at 15 days post inoculation were used for transcriptional analysis.