Hi! I am Mingkee, an MIBTP-PhD (Midlands Integrative Bio-resource Training Partnerhsip) student working in Gifford’s lab. I am following up a work from a previous study in Gifford's lab that investigated plant's control of nitrogen-fixing nodulation in Medicago truncatula. Using suites of genomic and phenotypic analyses, to reveal the differentially expressed genes under rhizobia and different nitrogen conditions could find six motifs. Since these genes were strongly rhizobia and nitrogen regulated, and their putative promoters were mainly genes involved in the nodulation pathway, we suggest that they may be regulators of nodule numbers depending on the plant N status. Of particular prevalence were Nodule Specific Cysteine Rich (NCR) peptides.
So, we propose that NCRs could be key molecules in controlling the nodulation and lateral root growth. We want to test if the novel motifs are functional in their control of NCR genes, discover the upstream regulatory molecules and ask if the regulatory effect has a significant effect on the ability of legumes to nodulate. Remarkably, root nodule symbiosis evolved in plants at least 5 times and is not restricted to legumes (reviewed in Lagunas et al 2015, J. Exp. Bot). We also want to identify these motifs are conserved across Medicago, to other legumes Chamaecrista fasciculata & Parasponia andersonii, a non-legume (which each evolved nodulation independently). Analysing nodulation/lateral root responses across Medicago with phenotypic and molecular methods will provide a valuable comparative resource.