Sub-theme 3b - Nutrient regulation of the chickpea rhizobia symbiosis
Specific sub-theme contributors:
Transport process involved in moving nutrients to, from and within the nodule impact on the efficiency of N2-fixation. Enhanced or specific expression of transport protein genes is key to the functioning of nodules in many legumes (Krusell et al., 2005; Benedito et al., 2010; Hakoyama et al., 2012; Brear et al., 2013; Courty et al., 2014) including chickpea (Afonso-Grunz et al., 2014). Within nodule cells, N2-fixing bacteroids are enclosed by a plant-derived symbiosome membrane (SM) that controls the exchange of compounds between the symbiotic partners. Transport of essential metabolites across the SM and its regulation are core determinants of the efficiency of N2-fixation and we have identified SM transporters that are essential for N2-fixation in soybean (Clarke et al., in press). Key areas that warrant investigation are supply of malate and metal ions to maintain bacteroid metabolism (Brear et al., 2013; Clarke et al., 2014), peptide transport that is essential for the symbiosis (Smith, Day et al. unpublished) and nitrate transport during establishment of the symbiosis (Bagchi et al., 2012) and across the SM (Vincill et al., 2005). We will use RNAseq, proteomics and targeted analysis of transporter genes and proteins to assess components important for effective N2-fixation in chickpea ideotypes with different efficiencies of N2-fixation in association with different rhizobial strains
Identification of key regulatory genes managing nutrient exchange in the nodule for the development of improved N2-fixation capacity in chickpea.