TY - JOUR

T1 - NCR Peptides - plant effectors governing terminal differentiation of nodule bacteria into the symbiotic form

T2 - (Review)

AU - Kliukova, M. S.

AU - Zhukov, V. A.

AU - Tikhonovich, I. A.

N1 - Funding Information: 1All-Russian Research Institute for Agricultural Microbiology, Federal Agency of Scientific Organizations, 3, sh. Podbel’skogo, St. Petersburg, 196608 Russia, e-mail: zhukoff01@yahoo.com, Zhukov@ARRIAM.ru (corresponding author); 2Saint-Petersburg State University, 7/9, Universitetskaya nab., St. Petersburg, 199034 Russia ORCID: Kliukova M.S. orcid.org/0000-0003-1119-5512 Zhukov V.A. orcid.org/0000-0002-2411-9191 The authors declare no conflict of interests Acknowledgements: Supported by Russian Science Foundation (grant ¹ 14-24-00135); V.A. Zhukov is supported by grant ¹ 14-04-01442-а form Russian Foundation for Basic Research Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2017

Y1 - 2017

N2 - Uptake of mineral nutrients from the soil is the challenge of plant survival. In particular, the availability of such macro-elements as nitrogen and phosphorus is the limiting factor for plant growth and development. Some plant genera overcome this limitation by establishing symbiotic relationships with microorganisms. A remarkable example of such symbiosis is one between legumes and rhizobia - A group of nitrogen fixing soil bacteria. Rhizobial penetration into roots of a specific host plant causes initiation of a specialized organ, symbiotic nodule. Within cells of symbiotic nodule free-living bacteria differentiate into a symbiotic form called bacteroids. Such organelle-like structures provide plants with fixed nitrogen in exchange for nutrients (B.J. Ferguson et al., 2010). A number of legumes form nodules, in which bacteria terminally (irreversibly) differentiate into bacteroids, thus losing the opportunity to return to the free-living state. Terminal differentiation of bacteroids begins soon after release of the rhizobia into plant cells and leads to morphological, physiological and genetic changes in bacterial cells. It has been shown that a large family of antimicrobial peptides of plants called Nodule-specific Cysteine-Rich peptides (NCR peptides) plays a key regulatory role in this process (P. Mergaert et al., 2003). Its representatives are similar in structure and mode of action to defensins - plant innate immunity factors; however, NCR genes are expressed only in nodules, which fact is reflected in their name. At the moment, about 700 genes encoding NCR peptides that are highly variable in their amino acid sequence but possess a distinct conservative cysteine motif required for the adoption of correct conformation were identified in the genome of the model legume Medicago truncatula Gaertn. NCR peptides are delivered to their intracellular target symbiosome (?ell compartments containing bacteroides) triggering the process of differentiation by interacting with the components of membranes and various intracellular targets of bacteria (D. Wang et al., 2010). The most studied member of this family in M. truncatula is MtNCR247 a cationic peptide with four cysteines forming two disulfide bonds in oxidized form. MtNCR247 affects transcription, translation and cell division processes in M. truncatula microsymbiont Sinorhizobium meliloti at low concentrations, and also exhibits antimicrobial activity at higher concentrations (A. Farkas et al., 2014). To date, NCR peptides are identified only in plants belonging to IRLC (Inverted Repeatlacking Clade) legumes which are characterized by terminal differentiation of bacteria into bacteroids. Probably, evolutionary acquisition of the variable gene family encoding NCR peptides has been the selective advantage of this group of plants.

AB - Uptake of mineral nutrients from the soil is the challenge of plant survival. In particular, the availability of such macro-elements as nitrogen and phosphorus is the limiting factor for plant growth and development. Some plant genera overcome this limitation by establishing symbiotic relationships with microorganisms. A remarkable example of such symbiosis is one between legumes and rhizobia - A group of nitrogen fixing soil bacteria. Rhizobial penetration into roots of a specific host plant causes initiation of a specialized organ, symbiotic nodule. Within cells of symbiotic nodule free-living bacteria differentiate into a symbiotic form called bacteroids. Such organelle-like structures provide plants with fixed nitrogen in exchange for nutrients (B.J. Ferguson et al., 2010). A number of legumes form nodules, in which bacteria terminally (irreversibly) differentiate into bacteroids, thus losing the opportunity to return to the free-living state. Terminal differentiation of bacteroids begins soon after release of the rhizobia into plant cells and leads to morphological, physiological and genetic changes in bacterial cells. It has been shown that a large family of antimicrobial peptides of plants called Nodule-specific Cysteine-Rich peptides (NCR peptides) plays a key regulatory role in this process (P. Mergaert et al., 2003). Its representatives are similar in structure and mode of action to defensins - plant innate immunity factors; however, NCR genes are expressed only in nodules, which fact is reflected in their name. At the moment, about 700 genes encoding NCR peptides that are highly variable in their amino acid sequence but possess a distinct conservative cysteine motif required for the adoption of correct conformation were identified in the genome of the model legume Medicago truncatula Gaertn. NCR peptides are delivered to their intracellular target symbiosome (?ell compartments containing bacteroides) triggering the process of differentiation by interacting with the components of membranes and various intracellular targets of bacteria (D. Wang et al., 2010). The most studied member of this family in M. truncatula is MtNCR247 a cationic peptide with four cysteines forming two disulfide bonds in oxidized form. MtNCR247 affects transcription, translation and cell division processes in M. truncatula microsymbiont Sinorhizobium meliloti at low concentrations, and also exhibits antimicrobial activity at higher concentrations (A. Farkas et al., 2014). To date, NCR peptides are identified only in plants belonging to IRLC (Inverted Repeatlacking Clade) legumes which are characterized by terminal differentiation of bacteria into bacteroids. Probably, evolutionary acquisition of the variable gene family encoding NCR peptides has been the selective advantage of this group of plants.

KW - Differentiation of bacteroides

KW - NCR-peptides

KW - Nitrogen-fixing nodules

KW - Regulation of symbiosis development

KW - Rhizobium-legume symbiosis

UR - http://www.scopus.com/inward/record.url?scp=85033597014&partnerID=8YFLogxK

U2 - 10.15389/agrobiology.2017.5.869eng

DO - 10.15389/agrobiology.2017.5.869eng

M3 - статья

AN - SCOPUS:85033597014

VL - 52

SP - 869

EP - 877

JO - СЕЛЬСКОХОЗЯЙСТВЕННАЯ БИОЛОГИЯ. СЕРИЯ: БИОЛОГИЯ РАСТЕНИЙ. СЕРИЯ: БИОЛОГИЯ ЖИВОТНЫХ

JF - СЕЛЬСКОХОЗЯЙСТВЕННАЯ БИОЛОГИЯ. СЕРИЯ: БИОЛОГИЯ РАСТЕНИЙ. СЕРИЯ: БИОЛОГИЯ ЖИВОТНЫХ

SN - 0131-6397

IS - 5

ER -