Sadikova D.S.; Lebedeva M.A.; Lutova L.A.
Saint Petersburg State University, Saint Petersburg, Russia
“Legumes are able to enter into symbiosis with nitrogen-fixing bacteria rhizobia to build the root nodules. Symbiotic nodules provide transfer of nitrogen from rhizobia, necessary to support plant growth. This ability makes legumes key species for natural and agricultural ecosystems and allows to reduce the application of nitrogen-containing fertilizers. In different model legumes, supernodulating mutants have been described that form excessive number of symbiotic nodules even at a high nitrogen content in the soil. These mutants appeared to be defective in genes encoding CLV1-like kinase that acts in the shoot and systemically, via long-distance regulation, inhibits the initiation of symbiotic nodules on the root, thereby limiting the number of developing nodules. The ligands of CLV1-like kinases are mobile CLE peptides that are produced in the root in response to rhizobial inoculation and moves to the shoot to induce AON. In addition, nitrate-induced CLE genes have been identified in model legumes, which inhibited nodulation when overexpressed. In our work we analyzed four homologues of CLE genes in Pisum sativum, which are closely related to nodulation-suppressing CLE in other legumes. The effect of nitrate on the expression of these CLE genes was evaluated. Expression analysis of these four CLE genes at different stages of nodule development in P. sativum showed that these genes upregulated in during nodulation. We designed overexpression constructs for PsCLE12 and PsCLE13 genes and obtained composite plants with transgenic roots overexpressing these genes. Our preliminary data show that overexpression of nodulation-specific PsCLE12 gene did not suppress nodulation on transgenic roots, whereas PsCLE13 overexpression decreased nodule number on transgenic roots. Therefore, these two close homologues might have diverse function in nodulation, and we are going to study the mechanisms of their action in pea nodule development.
This project was supported by the Ministry of Science and Higher Education of the Russian Federation (agreement № 075-15-2020-922) on providing a grant for the creation and development of a World-class Scientific Center “Agrotechnologies for the Future”.”
