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Role of microbial and plant signals in determination of highly specific symbiosis

Name
Igor
Surname
Tikhonovich
Scientific organization
1.All-Russia Research Institute for Agricultural Microbiology, 2.Saint-Petersburg State University
Academic degree
Academician
Position
Director of the Institute (ARRIAM)
Scientific discipline
Agricultural & Biological technologies
Topic
Role of microbial and plant signals in determination of highly specific symbiosis
Abstract
Signalling in symbiosis
Tikhonovich I.A.1,2, Dolgikh E.A.1, Zhukov V.A.1
1 All-Russia Research Institute for Agricultural Microbiology, Podbelsky chausse 3, 196608, St.-Petersburg, Pushkin, Russia.
2 Saint-Petersburg State University, Universitetskaya emb., 7-9, 199034, St.-Petersburg, Russia.
E-mail: 79688b919cccARRIAM2008@yandex.ru
Symbiotic receptor kinases play a crucial role in development of legume plants under cooperation with soil microorganisms. Investigation of their structure and functions can help in understanding how plant reacts to environmental conditions.
Keywords
symbiosis, legume plants, nodule bacteria, signalling, Nod factors, microbial colonization, symbiotic receptor kinases
Summary

Signalling in symbiosis
Tikhonovich I.A.1,2, Dolgikh E.A.1, Zhukov V.A.1
1 All-Russia Research Institute for Agricultural Microbiology, Podbelsky chausse 3, 196608, St.-Petersburg, Pushkin, Russia.
2 Saint-Petersburg State University, Universitetskaya emb., 7-9, 199034, St.-Petersburg, Russia.
E-mail: 79688b919cccARRIAM2008@yandex.ru

Symbiotic receptor kinases play a crucial role in development of legume plants under cooperation with soil microorganisms. In particular, receptor kinases determine the specificity of interactions with nodule bacteria, take part in signaling during symbiosis development and regulate the intensity of microbial colonization. Investigation of structure and functions of these kinases can help in understanding how plant reacts to environmental conditions, and also can be useful for breeding in conditions of sustainable agriculture. 

Specificity of interactions between legume plants and nodule bacteria is based on ligand-receptor interactions, during which the bacterial signal molecules are perceived by plant receptor kinases. Lipochitooligosaccharide signals emanating from rhizobia, known as Nod factors (NFs), trigger a complex of specific responses in the epidermis, pericycle and root cortex of the legume plants, thereby providing the basis for subsequent bacterial entry and organogenesis of root nodules. For many years it has been predicted that legume plants perceive NFs by means of high affinity receptors, triggering signal transduction pathway. Among the evidence is the fact that minor changes in NF structure can change rhizobial host range. Despite some candidate NF receptor genes enconding LysM-receptor-like kinases (LysM-RLKs) have been identified in pea Pisum sativum, the underlying mechanisms by which binding of ligand elicits signaling responses remains unclear.

The focus of our research is to unravel these highly specific mechanisms by which rhizobial NFs produced by the symbionts are perceived by the legume plants. To address this aim some new putative LysM-RLKs (K1 and LykX) have been found and characterised in pea. Also the natural polymorphism of these genes was examined in 99 pea genotypes that represent virtually all the diversity within the genus Pisum. As a result, it was demonstrated that the allelic state of LykX gene is associated with the ability of plants to form symbiosis with wide spectrum of bacterial strains.

The possible role of new receptors will be discussed. In particular, we propose the model for perception the NF molecule by various receptor complexes.

 

This study was supported by Russian Science Foundation [grant number 16-16-10043]