海峡生命科学前沿论坛第146讲（2019.10.8）-Discovery of new factors in legume nodulation
海峡联合研究院 发布时间: 2019-09-29 信息员:
Date: Oct 8th,2019
Venue：Conference Room 201
Title：Discovery of new factors in legume nodulation
Speaker： Brett J. Ferguson（Integrative Legume Research Group, School of Agriculture and Food Sciences, University of Queensland）
We use genetic, physiological and functional-genomic approaches to elucidate the mechanisms driving the development and regulation of legume nodules, with a primary focus on soybean. The host plant tightly regulates the number of nodules it forms following rhizobia-inoculation (autoregulation of nodulation) or nitrate-treatment (nitrogen-regulation of nodulation). Both processes commence with the production of a novel root-derived signal. We recently identified genes in soybean encoding CLAVATA3/ESR related (CLE) peptides that exhibit increased expression following rhizobia inoculation (GmRIC1 and GmRIC2) or inhibitory nitrate treatment (GmNIC1). Over-expression of these genes significantly reduces soybean nodule numbers. We established that CLE peptides often require post-translational modification with a triarabinose building block to exert their full activity. The rhizobia-induced CLE peptides act systemically through the shoot, whereas the nitrate-induced CLE peptide acts locally in the root. Interestingly, all three CLE peptides are perceived by the same LRR receptor kinase, called Nodulation Autoregulation Receptor Kinase (NARK). This perception results in the regulation of a microRNA, which inhibits further nodule formation. We also isolated and phenotypically characterized a new soybean line mutated in the paralogous gene of GmNARK, called GmCLAVATA1A. Comparisons between the genetic sequences and genomic environments of GmCLAVATA1A and various orthologues of NARK revealed a number of interesting similarities; however, the two soybean paralogues function in divergent molecular pathways. Perception of the nodulation-suppressive CLE peptides in the shoot leads to the regulation of miR2111, which is transported to the root where it regulates the mRNA level of TML to control nodule organogenesis. In addition to the nodulation-suppression CLE peptides, the complete CLE peptide-encoding gene families of soybean (84 genes), common bean (46 genes), Medicago truncatula (52), and Lotus japonicus (53) were identified and categorised, providing a platform to help functionally-characterise these critical developmental factors. Findings relating to our progress in identifying and characterising the abovementioned nodulation factors and novel CLE peptides will be presented.
The seminar will be delivered in English.