Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species and is distributed mainly around the Mediterranean Basin, and extending across temperate Eurasia and sub-Saharan Africa. The best-known member of the genus is alfalfa, an important forage crop, and the genus name is based on the Latin name for that plant, medica, from Greek: μηδική (πόα) Median (grass). Most members of the genus are low, creeping herbs, resembling clover, but with burs. However, alfalfa grows to a height of 1 meter, and tree medick is a shrub. Members of the genus are known to produce bioactive compounds such as medicarpin and medicagenic acid. Chromosome numbers in Medicago range from 2n = 14 to 48.
Leghemoglobin is an oxygen-carrying phytoglobin found in the nitrogen-fixing root nodules of leguminous plants. It is produced by these plants in response to the roots being colonized by nitrogen-fixing bacteria, termed rhizobia, as part of the symbiotic interaction between plant and bacterium: roots not colonized by Rhizobium do not synthesise leghemoglobin. Leghemoglobin has close chemical and structural similarities to hemoglobin, and, like hemoglobin, is red in colour. It was originally thought that the heme prosthetic group for plant leghemoglobin was provided by the bacterial symbiont within symbiotic root nodules. However, subsequent work shows that the plant host strongly expresses heme biosynthesis genes within nodules, and that activation of those genes correlates with leghemoglobin gene expression in developing nodules.
The meristem is a type of tissue found in plants. It consists of undifferentiated cells capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells continue to divide until a time when they get differentiated and then lose the ability to divide.
Medicago truncatula, the barrelclover, strong-spined medick, barrel medic, or barrel medick, is a small annual legume native to the Mediterranean region that is used in genomic research. It is a low-growing, clover-like plant 10–60 centimetres (3.9–23.6 in) tall with trifoliate leaves. Each leaflet is rounded, 1–2 centimetres (0.39–0.79 in) long, often with a dark spot in the center. The flowers are yellow, produced singly or in a small inflorescence of two to five together; the fruit is a small, spiny pod.
Ensifer meliloti are an aerobic, Gram-negative, and diazotrophic species of bacteria. S. meliloti are motile and possess a cluster of peritrichous flagella. S. meliloti fix atmospheric nitrogen into ammonia for their legume hosts, such as alfalfa. S. meliloti forms a symbiotic relationship with legumes from the genera Medicago, Melilotus and Trigonella, including the model legume Medicago truncatula. This symbiosis promotes the development of a plant organ, termed a root nodule. Because soil often contains a limited amount of nitrogen for plant use, the symbiotic relationship between S. meliloti and their legume hosts has agricultural applications. These techniques reduce the need for inorganic nitrogenous fertilizers.
Root nodules are found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known as rhizobia. This process has evolved multiple times within the legumes, as well as in other species found within the Rosid clade. Legume crops include beans, peas, and soybeans.
Nod factors, are signaling molecules produced by soil bacteria known as rhizobia in response to flavonoid exudation from plants under nitrogen limited conditions. Nod factors initiate the establishment of a symbiotic relationship between legumes and rhizobia by inducing nodulation. Nod factors produce the differentiation of plant tissue in root hairs into nodules where the bacteria reside and are able to fix nitrogen from the atmosphere for the plant in exchange for photosynthates and the appropriate environment for nitrogen fixation. One of the most important features provided by the plant in this symbiosis is the production of leghemoglobin, which maintains the oxygen concentration low and prevents the inhibition of nitrogenase activity.
The miR-9 microRNA, is a short non-coding RNA gene involved in gene regulation. The mature ~21nt miRNAs are processed from hairpin precursor sequences by the Dicer enzyme. The dominant mature miRNA sequence is processed from the 5' arm of the mir-9 precursor, and from the 3' arm of the mir-79 precursor. The mature products are thought to have regulatory roles through complementarity to mRNA. In vertebrates, miR-9 is highly expressed in the brain, and is suggested to regulate neuronal differentiation. A number of specific targets of miR-9 have been proposed, including the transcription factor REST and its partner CoREST.
Cinnamoyl-CoA reductase (EC 1.2.1.44), systematically named cinnamaldehyde:NADP+ oxidoreductase (CoA-cinnamoylating) but commonly referred to by the acronym CCR, is an enzyme that catalyzes the reduction of a substituted cinnamoyl-CoA to its corresponding cinnamaldehyde, utilizing NADPH and H+ and releasing free CoA and NADP+ in the process. Common biologically relevant cinnamoyl-CoA substrates for CCR include p-coumaroyl-CoA and feruloyl-CoA, which are converted into p-coumaraldehyde and coniferaldehyde, respectively, though most CCRs show activity toward a variety of other substituted cinnamoyl-CoA's as well. Catalyzing the first committed step in monolignol biosynthesis, this enzyme plays a critical role in lignin formation, a process important in plants both for structural development and defense response.
Peptide signaling plays a significant role in various aspects of plant growth and development and specific receptors for various peptides have been identified as being membrane-localized receptor kinases, the largest family of receptor-like molecules in plants. Signaling peptides include members of the following protein families.
Within genetics, post-genomic research has rendered bacterial small non-coding RNAs (sRNAs) as major players in post-transcriptional regulation of gene expression in response to environmental stimuli. The Alphaproteobacteria includes Gram-negative microorganisms with diverse life styles; frequently involving long-term interactions with higher eukaryotes.
In molecular biology mir-390 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
In molecular biology mir-408 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
In molecular biology mir-398 microRNA is a short RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms.
4′,7-Dihydroxyflavone is a flavone. It is found in Medicago truncatula in relation with the root nodulation symbiont Sinorhizobium meliloti or in seeds of Sophora viciifolia.
β-amyrin synthase is an enzyme with systematic name (3S)-2,3-epoxy-2,3-dihydrosqualene mutase . This enzyme catalyses the following chemical reaction
Ensifer medicae is a species of gram-negative, nitrogen-fixing, rod-shaped bacteria. They can be free-living or symbionts of leguminous plants in root nodules. E.medicae was first isolated from root nodules on plants in the genus Medicago. Some strains of E.medicae, like WSM419, are aerobic. They are chemoorganotrophic mesophiles that prefer temperatures around 28 °C. In addition to their primary genome, these organisms also have three known plasmids, sized 1,570,951 bp, 1,245,408 bp and 219,313 bp.
Martin Parniske is a German biologist with a specialisation in genetics, microbiology and biochemistry. He is university professor and head of the Institute of Genetics at the Faculty of Biology of the Ludwig Maximilian University of Munich. Parniske's scientific focus is on the molecular interaction between plants and symbiotic and pathogenic organisms including bacteria, fungi, oomycetes and insects.
A symbiosome is a specialised compartment in a host cell that houses an endosymbiont in a symbiotic relationship.
Yiliang Ding has been a group leader with tenure at the John Innes Centre since 2014, working on the functional roles of the RNA structure in living cells. She has also been an Honorary Group Leader at the Babraham Institute and an Honorary Associate Professor at the University of East Anglia since 2022.
