Ploidy is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present : monoploid, diploid, triploid, tetraploid, pentaploid, hexaploid, heptaploid or septaploid, etc. The generic term polyploid is often used to describe cells with three or more chromosome sets.
Polyploidy is a condition in which the cells of an organism have more than one pair of (homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one from each of two parents; each set contains the same number of chromosomes, and the chromosomes are joined in pairs of homologous chromosomes. However, some organisms are polyploid. Polyploidy is especially common in plants. Most eukaryotes have diploid somatic cells, but produce haploid gametes by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Males of bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis; the sporophyte generation is diploid and produces spores by meiosis.
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, are a large and agriculturally important family of flowering plants. It includes trees, shrubs, and perennial or annual herbaceous plants, which are easily recognized by their fruit (legume) and their compound, stipulate leaves. The family is widely distributed, and is the third-largest land plant family in number of species, behind only the Orchidaceae and Asteraceae, with about 765 genera and nearly 20,000 known species.
Caesalpinioideae is a botanical name at the rank of subfamily, placed in the large family Fabaceae or Leguminosae. Its name is formed from the generic name Caesalpinia. It is known also as the peacock flower subfamily. The Caesalpinioideae are mainly trees distributed in the moist tropics, but include such temperate species as the honeylocust and Kentucky coffeetree. It has the following clade-based definition:
The most inclusive crown clade containing Arcoa gonavensisUrb. and Mimosa pudicaL., but not Bobgunnia fistuloides(Harms) J. H. Kirkbr. & Wiersema, Duparquetia orchidaceaBaill., or Poeppigia proceraC.Presl
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.
The honey locust, also known as the thorny locust or thorny honeylocust, is a deciduous tree in the family Fabaceae, native to central North America where it is mostly found in the moist soil of river valleys. Honey locust is highly adaptable to different environments, has been introduced worldwide, and can be an aggressive, invasive species outside of its native range.
Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In general, they are gram negative, motile, non-sporulating rods.
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 symbionts, 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.
Lotus, a latinization of Greek lōtos, is a genus of flowering plants that includes most bird's-foot trefoils and deervetches and contains many dozens of species distributed worldwide. Depending on the taxonomic authority, roughly between 70 and 150 are accepted. Lotus is a genus of legumes and its members are adapted to a wide range of habitats, from coastal environments to high altitudes.
The triangle of U is a theory about the evolution and relationships among the six most commonly known members of the plant genus Brassica. The theory states that the genomes of three ancestral diploid species of Brassica combined to create three common tetraploid vegetables and oilseed crop species. It has since been confirmed by studies of DNA and proteins.
Bradyrhizobium is a genus of Gram-negative soil bacteria, many of which fix nitrogen. Nitrogen fixation is an important part of the nitrogen cycle. Plants cannot use atmospheric nitrogen (N2); they must use nitrogen compounds such as nitrates.
Actinorhizal plants are a group of angiosperms characterized by their ability to form a symbiosis with the nitrogen fixing actinomycetota Frankia. This association leads to the formation of nitrogen-fixing root nodules.
enod40, also known as early nodulin 40, is a gene found in flowering plants. The gene has characteristics of both protein and Non-coding RNA genes. There is some evidence that the non-coding characteristics of this gene are more widely conserved than the protein coding sequences. In soyabeans enod40 was found to be expressed during early stages of formation of nitrogen-fixing root nodules that are associated with symbiotic soil rhizobial bacteria. The gene is also active in roots containing fungi forming phosphate-acquiring arbuscular mycorrhiza. An interaction with a novel RNA-binding protein MtRBP1 investigated in the development of Root nodule suggests ENOD40 has a function of cytoplasmic relocalization of nuclear proteins. In the study of non-legume plants, the over-expression of ENOD40 in transgenic Arabidopsis lines was observed a reduction of cell expansion.
Mesorhizobium loti, formerly known as Rhizobium loti, is a Gram negative species of bacteria found in the root nodules of many plant species. Its name is a reference to Lotus corniculatus, a flowering plant from which it was originally isolated.
The inverted repeat-lacking clade(IRLC) is a monophyletic clade of the flowering plant subfamily Faboideae (or Papilionaceae). Faboideae includes the majority of agriculturally-cultivated legumes. The name of this clade is informal and is not assumed to have any particular taxonomic rank like the names authorized by the ICBN or the ICPN. The clade is characterized by the loss of one of the two 25-kb inverted repeats in the plastid genome that are found in most land plants. It is consistently resolved in molecular phylogenies. The clade is predicted to have diverged from the other legume lineages 39.0±2.4 million years ago (in the Eocene). It includes several large, temperate genera such as AstragalusL., HedysarumL., MedicagoL., OxytropisDC., SwainsonaSalisb., and TrifoliumL..
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.
