Attila Kereszt

• Hungarian Academy of Sciences

The Golden Gate method is an efficient tool for seamless assembly of multiple DNA fragments, which uses Type IIS restriction endonucleases, cleaving the DNA outside of their recognition site to release DNA parts from PCR fragments or entry clones, thus allowing the design of overhangs for ligation at will. However, the construction of the entry clo...

Host range specificity is a prominent feature of the legume-rhizobial symbiosis. Sinorhizobium meliloti and Sinorhizobium medicae are two closely related species that engage in root nodule symbiosis with legume plants of the Medicago genus, but certain Medicago species exhibit selectivity in their interactions with the two rhizobial species. We hav...

Symbiotic nitrogen fixation by Rhizobium bacteria in the cells of legume root nodules alleviates the need for nitrogen fertilizers. Nitrogen fixation requires the endosymbionts to differentiate into bacteroids which can be reversible or terminal. The latter is controlled by the plant, it is more beneficial and has evolved in multiple clades of the...

Plants have evolved the ability to distinguish between symbiotic and pathogenic microbial signals. However, potentially cooperative plant-microbe interactions often abort due to incompatible signaling. The Nodulation Specificity 1 (NS1) locus in the legume Medicago truncatula blocks tissue invasion and root nodule induction by many strains of the n...

Symbiotic nitrogen fixation by rhizobium bacteria within the cells of legume root nodules alleviates the need for nitrogen fertilizers. Nitrogen fixation requires the endosymbionts to differentiate into bacteroids and this can be reversible or terminal. The latter is controlled by the plant, is more beneficial and has evolved in a large clade of th...

The nitrogen-fixing symbiosis between leguminous plants and soil bacteria collectively called rhizobia plays an important role in the global nitrogen cycle and is an essential component of sustainable agriculture. Genetic determinants directing the development and functioning of the interaction have been identified with the help of a very limited n...

Legumes are able to meet their nitrogen need by establishing nitrogen-fixing symbiosis with rhizobia. Nitrogen fixation is performed by rhizobia, which has been converted to bacteroids, in newly formed organs, the root nodules. In the model legume Medicago truncatula, nodule cells are invaded by rhizobia through transcellular tubular structures cal...

Legume plants can form root organs called nodules where they house intracellular symbiotic rhizobium bacteria. Within nodule cells, rhizobia differentiate into bacteroids, which fix nitrogen for the benefit of the plant. Depending on the combination of host plants and rhizobial strains, the output of rhizobium-legume interactions varies from nonfix...

Legume plants can form root organs called nodules where they house intracellular symbiotic rhizobium bacteria. Within nodule cells, rhizobia differentiate into bacteroids, which fix nitrogen for the benefit of the plant. Depending on the combination of host plants and rhizobial strains, the output of rhizobium-legume interactions is varying from no...

BACKGROUND Cervical cancer (CC) remains a leading cause of gynaecological cancer-related mortality world wide and constitutes the third most common malignancy in women. The RAIDs consortium (http://www.raids-fp7.eu/) conducted a prospective European study [BioRAIDs (NCT02428842)] with the objective to stratify CC patients for innovative treatments....

Root nodules formed by plants of the nitrogen-fixing clade (NFC) are symbiotic organs whose function is the maintenance and metabolic integration of large populations of nitrogen-fixing bacteria. These organs feature unique characteristics and processes, including their tissue organization, the presence of specific infection structures called infec...

Legume-rhizobium symbiosis is a major ecological process, fueling the biogeochemical nitrogen cycle with reduced nitrogen. It also represents a promising strategy to reduce the use of chemical nitrogen fertilizers in agriculture, thereby improving its sustainability. This interaction leads to the intracellular accommodation of rhizobia within plant...

The development and functioning of the nitrogen fixing symbiosis between legume plants and soil bacteria collectively called rhizobia requires continuous chemical dialogue between the partners using different molecules such as flavonoids, lipo-chitooligosaccharides, polysaccharides and peptides. Agrobacterium rhizogenes mediated hairy root transfor...

Background: There is a lack of information as to which molecular processes, present at diagnosis, favor tumour escape from standard-of-care treatments in cervical cancer (CC). RAIDs consortium (www.raids-fp7.eu), conducted a prospectively monitored trial, [BioRAIDs (NCT02428842)] with the objectives to generate high quality samples and molecular a...

To circumvent the paucity of nitrogen sources in the soil legume plants establish a symbiotic interaction with nitrogen‐fixing soil bacteria called rhizobia. During symbiosis, the plants form root organs called nodules, where bacteria are housed intracellularly and become active nitrogen fixers known as bacteroids. Depending on their host plant, ba...

Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without...

Strain CCMM B554, also known as FSM-MA, is a soil dwelling and nodule forming, nitrogen-fixing bacterium isolated from the nodules of the legume Medicago arborea L. in the Maamora Forest, Morocco. The strain forms effective nitrogen fixing nodules on species of the Medicago, Melilotus and Trigonella genera and is exceptional because it is a highly...

Medicago truncatula shows a high level of specificity when interacting with its symbiotic partner Sinorhizobium meliloti. This specificity is mainly manifested at the nitrogen-fixing stage of nodule development, such that a particular bacterial strain forms nitrogen-fixing nodules (Nod+/Fix+) on one plant genotype but ineffective nodules (Nod+/Fix-...

Cervical cancer (CC) is the fourth most common cause of cancer deaths in women worldwide, for which prognostic and predictive biomarkers are largely lacking. RAIDs is a EU-funded project on cervical cancer that spans seven European countries. The main objective of the RAIDs project is to use this tumor type, which is easily accessible for repeated...

Significance Nitrogen is a limiting factor for plant growth. Most crops obtain their nitrogen through the use of nitrogen-based fertilizers, which is costly, and also causes environmental pollution. Legumes, however, have the unique ability to fix atmospheric nitrogen through symbioses with nitrogen-fixing bacteria. Although legumes can be nodulate...

Significance The mutualistic association between legumes and rhizobia has ecological and agronomical relevance because of its contribution to the global nitrogen cycle by biological nitrogen fixation. Legumes from the Inverted Repeat Lacking Clade (IRLC) impose irreversible differentiation to their endosymbionts through nodule-specific cysteine-ric...

Significance Polyploidization of somatic cells is common in angiosperms. The characteristic and inherited developmental pattern of polyploidy in various organs and cell types suggests a role for endoreduplication in differentiation and specialized cell functioning. Rhizobium -infected nodule cells provide a unique opportunity to study specific deve...

In the Medicago truncatula genome about 700 genes code for nodule-specific cysteine-rich (NCR) small peptides that are expressed in the symbiotic organ, the root nodule, where they control terminal differentiation of the endosymbiotic rhizobium bacteria to nitrogen-fixing bacteroids. Cationic NCR peptides were predicted to have antimicrobial activi...

Background: Cervical cancer (CC) remains a leading cause of gynaecological cancer-related mortality worldwide. CC pathogenesis is triggered when human papillomavirus (HPV) inserts into the genome, resulting in tumour suppressor gene inactivation and oncogene activation. Collecting tumour and blood samples is critical for identifying these genetic...

Background Certain legume plants produce a plethora of AMP-like peptides in their symbiotic cells. The cationic subgroup of the nodule-specific cysteine-rich (NCR) peptides has potent antimicrobial activity against gram-negative and gram-positive bacteria as well as unicellular and filamentous fungi. Findings It was shown by scanning and atomic fo...

Background Recent retrospective data1,2 identified major molecular alterations in cervical cancer (CC), but so far there has been no prospective assessment on patient outcome using a complete molecular profiling with quality control evaluation of treatment. The Cetuxicol (phase 2) clinical trial showed that the addition of Cetuximab over a 6 week p...

Medicago and closely related legume species from the inverted repeat-lacking clade (IRLC) impose terminal differentiation onto their bacterial endosymbionts manifested in genome endoreduplication, cell enlargement and loss of cell division capacity. Nodule-specific cysteine-rich secreted host peptides (NCR) are plant effectors of this process. As b...

Significance In certain legume–rhizobia symbioses, the host plant is thought to control the terminal differentiation of its bacterial partner leading to nitrogen fixation. In Medicago truncatula , over 600 genes coding for nodule-specific cysteine-rich (NCR) peptides are expressed during nodule development and have been implicated in bacteroid diff...

Leguminous plants live in symbiosis with nitrogen-fixing soil bacteria known as rhizobia. Symbiotic nitrogen fixation occurs in specialized root organs called nodules. Bacteria penetrate into the plant cells and are encapsulated by a plant-derived peribacteroid membrane forming an organelle-like structure, the symbiosome. Within the symbiosome, bac...

Antimicrobial peptides are small proteins that exhibit a broad spectrum of antimicrobial activity. Their chemical structure allows them to interact (attach and insert) with membranes. The fine details about this interaction and their mode of action are not fully clarified yet. In order to better understand this mechanism, we have performed in situ...

The symbiosis of Medicago truncatula with Sinorhizobium meliloti or S. medicae soil bacteria results in the formation of root nodules where bacteria inside the plant cells are irreversibly converted to polyploid, non-dividing nitrogen-fixing bacteroids. Bacteroid differentiation is host-controlled and the plant effectors are symbiosis-specific secr...

Next-Generation Sequencing (NGS) originally refers to high-throughput, massively parallel sequencing methods that allow the sequencing of up to billions of small (50-1000 bp), amplified DNA fragments at the same time but nowadays, there are NGS techniques that determine the sequence of long (up to 50 kbp) single molecules. Over the past years, NGS...

The increasing number of multidrug-resistant microbes now emerging necessitates the identification of novel antimicrobial agents. Plants produce a great variety of antimicrobial peptides including hundreds of small, nodule-specific cysteine-rich NCR peptides that, in the legume Medicago truncatula, govern the differentiation of endosymbiotic nitrog...

Supplementary Figure 1: Representative output of an RTCA experiment.

Significance Intracellular endosymbiotic bacteria in diverse symbiotic systems are under the control of host-derived symbiosis-specific peptides. These peptides have mostly unknown activities. In the facultative rhizobium-legume symbiosis, the bacteria differentiate in many legumes to large polyploid noncultivable bacteroids. This terminal differen...

Transcription factors (TFs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few TFs have been characterized functionally. Here, we describe REGULATOR OF SYMBIOSOME DIFFERENTIATION (RSD) of Medicago truncatula, a member of the Cysteine-2/Histidine-2 (C2H2) family of plant TFs that is required for normal...

Symbiosis between Rhizobium bacteria and legumes leads to the formation of the root nodule. The endosymbiotic bacteria reside in polyploid host cells as membrane-surrounded vesicles where they reduce atmospheric nitrogen to support plant growth by supplying ammonia in exchange for carbon sources and energy. The morphology and physiology of endosymb...

Leguminous plants establish symbiosis with nitrogen-fixing α- and β-Proteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. Members of the Inverted Repeat-Lacking Clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-ric...

Propionibacterium avidum is an anaerobic Gram-positive bacterium that forms part of the normal human cutaneous microbiota, colonizing moist areas such as the vestibule of the nose, axilla, and perineum. Here we present the complete genome sequence of P. avidum strain 44067, which was isolated from a carbuncle of the trunk.

Symbiosomes are organelle-like structures in the cytoplasm of legume nodule cells which are composed of the special, nitrogen-fixing forms of rhizobia called bacteroids, the peribacteroid space and the enveloping peribacteroid membrane of plant origin. The formation of these symbiosomes requires a complex and coordinated interaction between the two...

Rhizobium-legume symbiosis has been considered as a mutually favorable relationship for both partners. However, in certain phylogenetic groups of legumes, the plant directs the bacterial symbiont into an irreversible terminal differentiation. This is mediated by the actions of hundreds of symbiosis-specific plant peptides resembling antimicrobial p...

Antimicrobial peptides (AMPs) are ribosomally synthesized natural antibiotics that are crucial effectors of innate immune systems in all living organisms. AMPs are diverse peptides, differing in their amino acid composition and structure, that generally display rapid killing and broad-spectrum antimicrobial activities. Therefore, AMPs have high pot...

A single plant receptor recognizes related bacterial and fungal signals to initiate symbiosis.

Two allelic non-nodulating mutants, nod49 and rj1, were characterized using map-based cloning and candidate gene approaches, and genetic complementation. From our results we propose two highly related lipo-oligochitin LysM-type receptor kinase genes (GmNFR1α and GmNFR1β) as putative Nod factor receptor components in soybean. Both mutants contained...

*Legumes regulate the number of nodules they form via a process called autoregulation of nodulation (AON). This involves a shoot-derived inhibitor (SDI) molecule that is synthesized in the shoots and is transported down to the roots where it inhibits further nodule development. *To characterize SDI, we developed a novel feeding bioassay. This invol...

Legume Symbiosome Leguminous plants (peas and beans) are major players in global nitrogen cycling by virtue of their symbioses with nitrogen-fixing bacteria that are harbored in specialized structures, called nodules, on the plant's roots. Van de Velde et al. (p. 1122 ) show that the host plant, Medicago truncatula produces nodule-specific cysteine...

Chemically induced non-nodulating nod139 and nn5 mutants of soybean (Glycine max) show no visible symptoms in response to rhizobial inoculation. Both exhibit recessive Mendelian inheritance suggesting loss of function. By allele determination and genetic complementation in nod139 and nn5, two highly related lipo-oligochitin LysM-type receptor kinas...

Somatic embryogenesis (SE) is induced in vitro in Medicago truncatula 2HA by auxin and cytokinin but rarely in wild type Jemalong. The putative WUSCHEL (MtWUS), CLAVATA3 (MtCLV3) and the WUSCHEL-related homeobox gene WOX5 (MtWOX5) were investigated in M. truncatula (Mt) and identified by the similarity to Arabidopsis WUS, CLV3 and WOX5 in amino aci...

Legumes develop root nodules from pluripotent stem cells in the root pericycle in response to mitogenic activation by a decorated chitin-like nodulation factor synthesized in Rhizobium bacteria. The soybean genes encoding the receptor for such signals were cloned using map-based cloning approaches. Pluripotent cells in the root pericycle and the ou...

The NARK (nodule autoregulation receptor kinase) gene, a negative regulator of cell proliferation in nodule primordia in several legumes, encodes a receptor kinase that consists of an extracellular leucine-rich repeat and an intracellular serine/threonine protein kinase domain. The putative catalytic domain of NARK was expressed and purified as a m...

NORK in legumes encodes a receptor-like kinase that is required for Nod factor signaling and root nodule development. Using Medicago truncatula NORK as bait in a yeast two-hybrid assay, we identified 3-hydroxy-3-methylglutaryl CoA reductase 1 (Mt HMGR1) as a NORK interacting partner. HMGR1 belongs to a multigene family in M. truncatula, and differe...

Nodulation and concomitant symbiotic nitrogen fixation are critical for the productivity of the legume, yielding food, feed and fuel. The nodule number in legumes is regulated by numerous factors including the number and efficiency of the interacting Rhizobium bacteria and abiotic stresses as well as endogenous processes involving phytohormones, no...

Rhizobial bacteria activate the formation of nodules on the appropriate host legume plant, and this requires the bacterial signaling molecule Nod factor. Perception of Nod factor in the plant leads to the activation of a number of rhizobial-induced genes. Putative transcriptional regulators in the GRAS family are known to function in Nod factor sig...

This protocol is used to induce transgenic roots on soybean to study the function of genes required in biological processes of the root. Young seedlings with unfolded cotyledons are infected at the cotyledonary node and/or hypocotyl with Agrobacterium rhizogenes carrying the gene construct to be tested and the infection sites are kept in an environ...

Strategies to introduce genes into non-embryogenic plants for complementation of a mutation are described and tested on tetraploid alfalfa (Medicago sativa). Genes conditioning embryogenic potential, a mutant phenotype, and a gene to complement the mutation can be combined using several different crossing and selection steps. In the successful stra...

The increased amount of data produced by large genome sequencing projects allows scientists to carry out important syntenic studies to a great extent. Detailed genetic maps and entirely or partially sequenced genomes are compared, and macro- and microsyntenic relations can be determined for different species. In our study, the syntenic relationship...