The tomato is the edible red, berry of the plant Solanum lycopersicum known as a tomato plant. The species originated in western South America; the Nahuatl word tomatl gave rise to the Spanish word tomate, from which the English word tomato derived. Its use as a cultivated food may have originated with the indigenous peoples of Mexico; the Spanish encountered the tomato from their contact with the Aztec during the Spanish colonization of the Americas and brought it to Europe. From there, the tomato was introduced to other parts of the European-colonized world during the 16th century; the tomato is consumed in diverse ways, raw or cooked, in many dishes, sauces and drinks. While tomatoes are fruits — botanically classified as berries — they are used as a vegetable ingredient or side dish. Numerous varieties of the tomato plant are grown in temperate climates across the world, with greenhouses allowing for the production of tomatoes throughout all seasons of the year. Tomato plants grow to 1–3 meters in height.
They are vines that have a weak stem that sprawls and needs support. Indeterminate tomato plants are cultivated as annuals. Determinate, or bush, plants are annuals that stop growing at a certain height and produce a crop all at once; the size of the tomato varies according to the cultivar, with a range of 0.5–4 inches in width. The word "tomato" comes from the Spanish tomate, which in turn comes from the Nahuatl word tomatl, meaning "the swelling fruit"; the native Mexican tomatillo is tomate. When Aztecs started to cultivate the Andean fruit to be larger and red, they called the new species xitomatl; the scientific species epithet lycopersicum is interpreted from Latin in the 1753 book, Species Plantarum, as "wolfpeach", where wolf is from lyco and peach is from persicum. The usual pronunciations of "tomato" are and; the word's dual pronunciations were immortalized in Ira and George Gershwin's 1937 song "Let's Call the Whole Thing Off" and have become a symbol for nitpicking pronunciation disputes.
In this capacity, it has become an American and British slang term: saying "" when presented with two choices can mean "What's the difference?" or "It's all the same to me". Botanically, a tomato is a fruit—a berry, consisting of the ovary, together with its seeds, of a flowering plant. However, the tomato is considered a "culinary vegetable" because it has a much lower sugar content than culinary fruits. Tomatoes are not the only food source with this ambiguity; this has led to legal dispute in the United States. In 1887, U. S. tariff laws that imposed a duty on vegetables, but not on fruit, caused the tomato's status to become a matter of legal importance. The U. S. Supreme Court settled this controversy on May 10, 1893, by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use—they are served with dinner and not dessert; the holding of this case applies only to the interpretation of the Tariff of 1883, the court did not purport to reclassify the tomato for botanical or other purposes.
Tomato plants are vines decumbent growing 180 cm or more above the ground if supported, although erect bush varieties have been bred 100 cm tall or shorter. Indeterminate types are "tender" perennials, dying annually in temperate climates, although they can live up to three years in a greenhouse in some cases. Determinate types are annual in all climates. Tomato plants are dicots, grow as a series of branching stems, with a terminal bud at the tip that does the actual growing; when that tip stops growing, whether because of pruning or flowering, lateral buds take over and grow into other functional, vines. Tomato vines are pubescent, meaning covered with fine short hairs; these hairs facilitate the vining process, turning into roots wherever the plant is in contact with the ground and moisture if the vine's connection to its original root has been damaged or severed. Most tomato plants have compound leaves, are called regular leaf plants, but some cultivars have simple leaves known as potato leaf style because of their resemblance to that particular relative.
Of RL plants, there are variations, such as rugose leaves, which are grooved, variegated, angora leaves, which have additional colors where a genetic mutation causes chlorophyll to be excluded from some portions of the leaves. The leaves are 10–25 cm long, odd pinnate, with five to 9 leaflets on petioles, each leaflet up to 8 cm long, with a serrated margin, their flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounding the pistil's style. Flowers in domestic cultivars can be self-fertilizing; the flowers are 1–2 cm across, with five pointed lobes on the corolla. Tomato fruit is classified as a berry; as a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising
Solanum wallacei known as Catalina nightshade, Wallace's nightshade, Northern island nightshade, or wild tomato, is a perennial plant that produces purple flowers, but otherwise resembles a tomato plant. The foliage and purple-black berries are poisonous; this rare plant is native to canyons and hillsides on two of the three Channel Islands of California, as well as Guadalupe Island off Baja California. It blooms in May. Wallace's nightshade is named for William Allen Wallace who collected samples from the Los Angeles area around 1854. Named for him is the woolly daisy, among others. Jepson Manual Treatment Solanum wallacei Catalina Island Conservancy Sources of botanical names - W
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
The cherry tomato is a type of small round tomato believed to be an intermediate genetic admixture between wild currant-type tomatoes and domesticated garden tomatoes. Cherry tomatoes range in size from a thumbtip up to the size of a golf ball, can range from spherical to oblong in shape. Although red, other varieties such as yellow and black exist; those shaped like an oblong share characteristics with plum tomatoes and are known as grape tomatoes. The berry tomato is regarded as a botanical variety of the cultivated berry, Solanum lycopersicum var. cerasiforme. Cherry tomatoes are believed to have been cultivated by the Aztecs in Mexico in the 15th century; the first tomatoes grown in Europe were yellow cherry tomatoes. Cherry tomatoes have been popular in the United States since at least 1919. Recipes using cherry tomatoes can be found in articles dating back to 1967; the Tomaccio tomato was developed by Nahum Kedar and Chaim Rabinovitch of the Agriculture Faculty of the Hebrew University of Jerusalem on its Rehovot Campus.
It is the result of a 12-year breeding program using wild Peruvian tomato species to create a sweet snack tomato with improved ripening time and shelf life. The Super Sweet 100 is a hybrid cultivar popular in the United States resistant to both Fusarium and Verticillium wilt; the Selke Biodynamic cherry tomato is named after Margrit Selke. The indeterminate hybrid sungold cherry tomato is known for its vigorous early-yielding plants and colorful orange fruits. List of tomato cultivars Pear tomato Media related to Solanum lycopersicum var. cerasiforme at Wikimedia Commons
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology, used to determine the order of the four bases: adenine, guanine and thymine; the advent of rapid DNA sequencing methods has accelerated biological and medical research and discovery. Knowledge of DNA sequences has become indispensable for basic biological research, in numerous applied fields such as medical diagnosis, forensic biology and biological systematics; the rapid speed of sequencing attained with modern DNA sequencing technology has been instrumental in the sequencing of complete DNA sequences, or genomes, of numerous types and species of life, including the human genome and other complete DNA sequences of many animal and microbial species. The first DNA sequences were obtained in the early 1970s by academic researchers using laborious methods based on two-dimensional chromatography. Following the development of fluorescence-based sequencing methods with a DNA sequencer, DNA sequencing has become easier and orders of magnitude faster.
DNA sequencing may be used to determine the sequence of individual genes, larger genetic regions, full chromosomes, or entire genomes of any organism. DNA sequencing is the most efficient way to indirectly sequence RNA or proteins. In fact, DNA sequencing has become a key technology in many areas of biology and other sciences such as medicine and anthropology. Sequencing is used in molecular biology to study genomes and the proteins they encode. Information obtained using sequencing allows researchers to identify changes in genes, associations with diseases and phenotypes, identify potential drug targets. Since DNA is an informative macromolecule in terms of transmission from one generation to another, DNA sequencing is used in evolutionary biology to study how different organisms are related and how they evolved; the field of metagenomics involves identification of organisms present in a body of water, dirt, debris filtered from the air, or swab samples from organisms. Knowing which organisms are present in a particular environment is critical to research in ecology, epidemiology and other fields.
Sequencing enables researchers to determine which types of microbes may be present in a microbiome, for example. Medical technicians may sequence genes from patients to determine if there is risk of genetic diseases; this is a form of genetic testing. DNA sequencing may be used along with DNA profiling methods for forensic identification and paternity testing. DNA testing has evolved tremendously in the last few decades to link a DNA print to what is under investigation; the DNA patterns in fingerprint, hair follicles, etc. uniquely separate each living organism from another. Testing DNA is a technique which can detect specific genomes in a DNA strand to produce a unique and individualized pattern; every living organism created has a one of a kind DNA pattern, which can be determined through DNA testing. It is rare that two people have the same DNA pattern, therefore DNA testing is successful; the canonical structure of DNA has four bases: thymine, adenine and guanine. DNA sequencing is the determination of the physical order of these bases in a molecule of DNA.
However, there are many other bases. In some viruses, cytosine may be replaced by hydroxy methyl glucose cytosine. In mammalian DNA, variant bases with methyl groups or phosphosulfate may be found. Depending on the sequencing technique, a particular modification, e.g. the 5mC common in humans, may or may not be detected. Deoxyribonucleic acid was first discovered and isolated by Friedrich Miescher in 1869, but it remained understudied for many decades because proteins, rather than DNA, were thought to hold the genetic blueprint to life; this situation changed after 1944 as a result of some experiments by Oswald Avery, Colin MacLeod, Maclyn McCarty demonstrating that purified DNA could change one strain of bacteria into another. This was the first time. In 1953, James Watson and Francis Crick put forward their double-helix model of DNA, based on crystallized X-ray structures being studied by Rosalind Franklin – and without crediting her. According to the model, DNA is composed of two strands of nucleotides coiled around each other, linked together by hydrogen bonds and running in opposite directions.
Each strand is composed of four complementary nucleotides – adenine, cytosine and thymine – with an A on one strand always paired with T on the other, C always paired with G. They proposed such a structure allowed each strand to be used to reconstruct the other, an idea central to the passing on of hereditary information between generations; the foundation for sequencing proteins was first laid by the work of Frederick Sanger who by 1955 had completed the sequence of all the amino acids in insulin, a small protein secreted by the pancreas. This provided the first conclusive evidence that proteins were chemical entities with a specific molecular pattern rather than a random mixture of material suspended in fluid. Sanger's success in sequencing insulin electrified x-ray crystallographers, including Watson and Crick who by now were trying to understand how DNA directed the formation of proteins within a cell. Soon after attending a series of lectures given by Frederick Sanger in October 1954, Crick began to develo
The flowering plants known as angiosperms, Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 64 orders, 416 families 13,164 known genera and c. 369,000 known species. Like gymnosperms, angiosperms are seed-producing plants. However, they are distinguished from gymnosperms by characteristics including flowers, endosperm within the seeds, the production of fruits that contain the seeds. Etymologically, angiosperm means a plant; the term comes from the Greek words sperma. The ancestors of flowering plants diverged from gymnosperms in the Triassic Period, 245 to 202 million years ago, the first flowering plants are known from 160 mya, they diversified extensively during the Early Cretaceous, became widespread by 120 mya, replaced conifers as the dominant trees from 100 to 60 mya. Angiosperms differ from other seed plants in several ways, described in the table below; these distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans.
Angiosperm stems are made up of seven layers. The amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms; the vascular bundles of the stem are arranged such that the phloem form concentric rings. In the dicotyledons, the bundles in the young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium. By the formation of a layer of cambium between the bundles, a complete ring is formed, a regular periodical increase in thickness results from the development of xylem on the inside and phloem on the outside; the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth, called annual rings.
Among the monocotyledons, the bundles are more numerous in the young stem and are scattered through the ground tissue. They once formed the stem increases in diameter only in exceptional cases; the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, provide the most trustworthy external characteristics for establishing relationships among angiosperm species; the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally from the axil of a leaf; as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. More the flower-bearing portion of the plant is distinguished from the foliage-bearing or vegetative portion, forms a more or less elaborate branch-system called an inflorescence. There are two kinds of reproductive cells produced by flowers. Microspores, which will divide to become pollen grains, are the "male" cells and are borne in the stamens.
The "female" cells called megaspores, which will divide to become the egg cell, are contained in the ovule and enclosed in the carpel. The flower may consist only of these parts, as in willow, where each flower comprises only a few stamens or two carpels. Other structures are present and serve to protect the sporophylls and to form an envelope attractive to pollinators; the individual members of these surrounding structures are known as petals. The outer series is green and leaf-like, functions to protect the rest of the flower the bud; the inner series is, in general, white or brightly colored, is more delicate in structure. It functions to attract bird pollinators. Attraction is effected by color and nectar, which may be secreted in some part of the flower; the characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans. While the majority of flowers are perfect or hermaphrodite, flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization.
Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot transfer pollen to the pistil. Homomorphic flowers may employ a biochemical mechanism called self-incompatibility to discriminate between self and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers; the botanical term "Angiosperm", from the Ancient Greek αγγείον, angeíon and σπέρμα, was coined in the form Angiospermae by Paul Hermann in 1690, as the name of one of his primary divisions of the plant kingdom. This included flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits, the whole fruit or each of its pieces being here regarded as a seed and naked; the term and its antonym were maintained by Carl Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any