W437 Genetic Components of Developmental Signaling for Nodulation and Nodal Identity Control in Soybean

Date: Sunday, January 15, 2012
Time: 8:00 AM
Room: Pacific Salon 1
Peter M. Gresshoff , CILR - The University of Queensland, Australia
Dugald E Dugald , CILR - The University of Queensland, Australia
Yu-Hsiang Lin , CILR - The University of Queensland, Australia
Satomi Hayashi , CILR - The University of Queensland, Australia
Saeid Mirzaei , CILR - The University of Queensland, Australia
Dongxue Li , CILR - The University of Queensland, Australia
Alina Tollenaere , CILR - The University of Queensland, Australia
Meng-Han Lin , CILR - The University of Queensland, Australia
Jacqueline Batley , CILR - The University of Queensland, Australia
Khalid Meksem , Southern Illinois University, Carbondale IL USA
Brett J. Ferguson , CILR - The University of Queensland, Australia
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Legumes, such as soybean, regulate the number of nitrogen fixing nodules via a systemic process called ‘Autoregulation Of Nodulation’ (AON), which commences following Bradyrhizobium-inoculation with the production of a root-derived signal called Q (1) and it subsequent perception by a LRR-RK called GmNARK (related genes, namely PvNARK, LjHAR1, MtSUNN, and PsSYM28 exist in other legumes. We identified novel soybean genes that are differentially expressed in the critical ‘zone of nodulation initiation’ (ZON) following rhizobia-inoculation and identified Q candidate genes encoding CLAVATA3/ESR related (CLE) peptides (see talk by D. Reid; Functional Genomics workshop).  Overexpression of the CLE genes significantly reduces soybean nodule numbers in a NARK-dependent manner (2). Evidence for transport or binding to NARK receptor does not exist yet. GmNARK has a paralogous gene GmCLV1A. We used TILLING to isolate a mutant in a putative N-glycosylation site (S562L), and found severe alteration of nodal identity control, including basal branching, flowering, and aberrant leaf formation. This suggests neodiversification. Upon Q perception by NARK a novel signal called ‘Shoot-Derived Inhibitor’ (SDI) is produced and exported to the root. SDI is water-extractable, petiole-feed transferable, NARK- and Nod factor-dependent, heat stable, small (3). Our results suggest common regulatory components for diverse meristem control involving LRR-RKs and CLE peptides.

1) Ferguson, B.J., Indrasumunar, A, Hayashi, S., Lin, M.-H., Lin, Y.-H., Reid, D.E., and Gresshoff, P.M. (2010) Genetic analysis of legume nodule development and autoregulation. J. Integrative Plant Biology 52: 61-76.

2) Reid, D.E., Ferguson, B.J. and Gresshoff, P.M. (2011) Inoculation- and nitrate-induced CLE peptides of soybean control NARK-dependent nodule formation. Mol. Plant Microbe Interactions 24: 606-618.

3) Lin, Y.-H., Ferguson, B.J., Kereszt, A. and Gresshoff, P.M. (2010) Suppression of supernodulation in soybean by a leaf-extracted, NARK- and Nod-factor-dependent small molecular fraction. New Phytol. 185: 1074-1086.

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