Solanaceae

The Solanaceae , or nightshades, are a family of flowering plants that ranges from annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includes a number of agricultural crops, medicinal plants, spices, weeds, and ornamentals. Many members of the family contain potent alkaloids, and some are highly toxic, but many—including tomatoes, potatoes, eggplant, bell and chili peppers—are used as food. The family belongs to the order Solanales, in the asterid group and class Magnoliopsida ( dicotyledons). The Solanaceae consists of about 98 genera and some 2,700 species, with a great diversity of habitats, morphology and ecology.

The name Solanaceae derives from the genus ''Solanum''. The etymology of the Latin word is unclear. The name may come from a perceived resemblance of certain solanaceous flowers to the sun and its rays. At least one species of ''Solanum'' is known as the "sunberry". Alternatively, the name could originate from the Latin verb ''solare'', meaning "to soothe", presumably referring to the soothing pharmacological properties of some of the psychoactive species of the family.

This family has a worldwide distribution, being present on all continents except Antarctica. The greatest diversity in species is found in South America and Central America. In 2017, scientists reported on their discovery and analysis of a fossil species belonging to the living genus ''Physalis'', ''Physalis infinemundi'', found in the Patagonian region of Argentina, dated to 52 million years ago. The finding has pushed back the earliest appearance of the plant family Solanaceae.

The Solanaceae family includes a number of commonly collected or cultivated species. The most economically important genus of the family is ''Solanum'', which contains the potato (''S. tuberosum'', in fact, another common name of the family is the "potato family"), the tomato (''S. lycopersicum''), and the eggplant or aubergine (''S. melongena''). Another important genus, ''Capsicum'', produces both chili peppers and bell peppers.

The genus ''Physalis'' produces the so-called groundcherries, as well as the tomatillo (''Physalis philadelphica''), ''Physalis peruviana'' (Cape gooseberry) and ''Physalis alkekengi'' (Chinese lantern). The genus '' Lycium'' contains the boxthorns and the goji berry, ''Lycium barbarum''. ''Nicotiana'' contains, among other species, tobacco.
Some other important members of Solanaceae include a number of ornamental plants such as ''Petunia'', ''Browallia'', and ''Lycianthes'', and sources of psychoactive alkaloids, ''Datura'', '' Mandragora'' (mandrake), and ''Atropa belladonna'' (deadly nightshade). Certain species are widely known for their medicinal uses, their psychotropic effects, or for being poisonous.

Most of the economically important genera are contained in the subfamily Solanoideae, with the exceptions of tobacco (''Nicotiana tabacum'', Nicotianoideae) and petunia (''Petunia'' × ''hybrida'', Petunioideae).

Many of the Solanaceae, such as tobacco and petunia, are used as model organisms in the investigation of fundamental biological questions at the cellular, molecular, and genetic levels.

Etymology and pronunciation

The name "Solanaceae" () comes to international scientific vocabulary from New Latin, from ''Solanum'', the type genus, + '' -aceae'', a standardized suffix for plant family names in modern taxonomy. The genus name comes from the Classical Latin word ''solanum'', referring to nightshades (especially ''Solanum nigrum''), "probably from sol, 'sun', + '' -anum'', neuter of '' -anus''."

Description

Plants in the Solanaceae can take the form of herbs, shrubs, trees, vines and lianas, and sometimes epiphytes. They can be annuals, biennials, or perennials, upright or decumbent. Some have subterranean tubers. They do not have laticifers, nor latex, nor coloured saps.
They can have a basal or terminal group of leaves or neither of these types. The leaves are generally alternate or alternate to opposed (that is, alternate at the base of the plant and opposed towards the inflorescence). The leaves can be herbaceous, leathery, or transformed into spines. The leaves are generally petiolate or subsessile, rarely sessile. They are frequently inodorous, but some are aromatic or fetid. The foliar lamina can be either simple or compound, and the latter can be either pinnatifid or ternate. The leaves have reticulated venation and lack a basal meristem. The laminae are generally dorsiventral and lack secretory cavities. The stomata are generally confined to one of a leaf's two sides; they are rarely found on both sides.

The flowers are generally hermaphrodites, although some are monoecious, andromonoecious, or dioecious species (such as some ''Solanum'' or ''Symonanthus''). Pollination is entomophilous. The flowers can be solitary or grouped into terminal, cymose, or axillary inflorescences. The flowers are medium-sized, fragrant (''Nicotiana''), fetid (''Anthocercis''), or inodorous. The flowers are usually actinomorphic, slightly zygomorphic, or markedly zygomorphic (for example, in flowers with a bilabial corolla in ''Schizanthus'' species). The irregularities in symmetry can be due to the androecium, to the perianth, or both at the same time. In the great majority of species, the flowers have a differentiated perianth with a calyx and corolla (with five sepals and five petals, respectively) an androecium with five stamens and two carpels forming a gynoecium with a superior ovary (they are therefore referred to as pentamers and tetracyclic). The stamens are epipetalous and are typically present in multiples of four or five, most commonly four or eight. They usually have a hypogynous disk. The calyx is gamosepalous (as the sepals are joined forming a tube), with the (4)5(6) segments equal, it has five lobes, with the lobes shorter than the tube, it is persistent and often accrescent. The corolla usually has five petals that are also joined forming a tube. Flower shapes are typically rotate (wheel-shaped, spreading in one plane, with a short tube) or tubular (elongated cylindrical tube), campanulated or funnel-shaped.

The androecium has (2)(4)5(6) free stamens within it opposite sepals (they alternate with the petals). They are usually fertile or, in some cases (for example in Salpiglossideae) they have staminodes. In the latter case, there is usually either one staminode (''Salpiglossis'') or three (''Schizanthus''). The anthers touch on their upper end forming a ring, or they are completely free, dorsifixed, or basifixed with poricide dehiscence or through small longitudinal cracks. The stamen's filament can be filliform or flat. The stamens can be inserted inside the coralline tube or exserted. The plants demonstrate simultaneous microsporogenesis, the microspores are tetrad, tetrahedral, or isobilateral. The pollen grains are bicellular at the moment of dehiscence, usually open and angular.

The gynoecium is bicarpelar (rarely three- or five-locular) with a superior ovary and two locules, which may be secondarily divided by false septa, as is the case for Nicandreae and Datureae. The gynoecium is located in an oblique position relative to the flower's median plane. They have one style and one stigma; the latter is simple or bilobate. Each locule has one to 50 ovules that are anatropous or hemianatropous with axillar placentation. The development of the embryo sack can be the same as for ''Polygonum'' or ''Allium'' species. The embryo sack's nuclear poles become fused before fertilization. The three antipodes are usually ephemeral or persistent as in the case of ''Atropa''. The fruit can be a berry as in the case of the tomato or wolfberry a dehiscent capsule as in ''Datura'', or a drupe. The fruit has axial placentation. The capsules are normally septicidal or rarely loculicidal or valvate. The seeds are usually endospermic, oily (rarely starchy), and without obvious hairs. The seeds of most Solanaceae are round and flat, about in diameter. The embryo can be straight or curved, and has two cotyledons. Most species in the Solanaceae have 2n=24 chromosomes, but the number may be a higher multiple of 12 due to polyploidy. Wild potatoes, of which there are about 200, are predominantly diploid (2 × 12 = 24 chromosomes), but triploid (3 × 12 = 36 chromosomes), tetraploid (4 × 12 = 48 chromosomes), pentaploid (5 × 12 = 60) and even hexaploid (6 × 12 = 72 chromosome) species or populations exist. The cultivated species ''Solanum tuberosum'' has 4 × 12 = 48 chromosomes. Some ''Capsicum'' species have 2 × 12 = 24 chromosomes, while others have 26 chromosomes.

Diversity of characteristics

Despite the previous description, the Solanaceae exhibit a large morphological variability, even in their reproductive characteristics. Examples of this diversity include: Hunziker, A.T. 1979: South American Solanaceae: a synoptic review. In: D'ARCY, W.G., 1979: The Biology and Taxonomy of the Solanaceae. Linn. Soc. Symp. Ser. 7: p 48-85. Linnean Soc. & Academic Press; London.Balken, J.A. THE PLANT FAMILY SOLANACEAE:
FRUITS IN SOLANACEAE

* The number of carpels that form the gynoecium
In general, the Solanaceae have a gynoecium (the female part of the flower) formed of two carpels. However, ''Melananthus'' has a monocarpelar gynoecium, there are three or four carpels in ''Capsicum'', three to five in ''Nicandra'', some species of '' Jaborosa'' and '' Trianaea'' and four carpels in ''Iochroma umbellatum''.

* The number of locules in the ovary

The number of locules in the ovary is usually the same as the number of carpels. However, some species occur in which the numbers are not the same due to the existence of false septa (internal walls that subdivide each locule), such as in ''Datura'' and some members of the Lycieae (the genera ''Grabowskia'' and ''Vassobia'').

* Type of ovules and their number
The ovules are generally inverted, folded sharply backwards (anatropous), but some genera have ovules that are rotated at right angles to their stalk (campilotropous) as in ''Phrodus'', ''Grabowskia'' or ''Vassobia''), or are partially inverted (hemitropous as in ''Cestrum'', ''Capsicum'', '' Schizanthus'' and ''Lycium''). The number of ovules per locule also varies from a few (two pairs in each locule in ''Grabowskia'', one pair in each locule in ''Lycium'') and very occasionally only one ovule is in each locule as for example in ''Melananthus''.

* The type of fruit
The fruits of the great majority of the Solanaceae are berries or capsules (including pyxidia) and less often drupes.
Berries are common in the subfamilies Cestroideae, Solanoideae (with the exception of ''Datura'', ''Oryctus'', ''Grabowskia'' and the tribe Hyoscyameae) and the tribe Juanulloideae (with the exception of '' Markea'').
Capsules are characteristic of the subfamilies Cestroideae (with the exception of ''Cestrum'') and Schizanthoideae, the tribes Salpiglossoideae and Anthocercidoideae, and the genus ''Datura''. The tribe Hyoscyameae has pyxidia.
Drupes are typical of the Lycieae tribe and in Iochrominae.

Alkaloids

Alkaloids are nitrogenous organic substances produced by plants as a secondary metabolite and which have an intense physiological action on animals even at low doses. Solanaceae are known for having a diverse range of alkaloids. To humans, these alkaloids can be desirable, toxic, or both. The tropanes are the most well-known of the alkaloids found in the Solanaceae. The plants that contain these substances have been used for centuries as poisons. However, despite being recognized as poisons, many of these substances have invaluable pharmaceutical properties. Many species contain a variety of alkaloids that can be more or less active or poisonous, such as scopolamine, atropine, hyoscyamine, and nicotine. They are found in plants such as henbane ('' Hyoscyamus albus''), belladonna (''Atropa belladonna''), jimson weed (''Datura stramonium''), mandrake (''Mandragora autumnalis''), tobacco, and others. Some of the main types of alkaloids are:

* Solanine: A toxic glycoalkaloid with a bitter taste, it has the formula C₄₅H₇₃NO₁₅. It is formed by the alkaloid solanidine with a carbohydrate side chain. It is found in leaves, fruit, and tubers of various Solanaceae such as the potato and tomato. Its production is thought to be an adaptive defence strategy against herbivores. Substance intoxication from solanine is characterized by gastrointestinal disorders (diarrhoea, vomiting, abdominal pain) and neurological disorders (hallucinations and headache). The median lethal dose is between 2 and 5 mg/kg of body weight. Symptoms become manifest 8 to 12 hours after ingestion. The amount of these glycoalkaloids in potatoes, for example, varies significantly depending on environmental conditions during their cultivation, the length of storage, and the variety. The average glycoalkaloid concentration is 0.075 mg/g of potato.Zeiger, E. 1998. Solanine and Chaconine. Review of Toxicological Literature. Integrated Laboratory Systems, USA. Solanine has occasionally been responsible for poisonings in people who ate berries from species such as ''Solanum nigrum'' or '' Solanum dulcamara'', or green potatoes.

* Tropanes: The term "tropane" comes from a genus in which they are found, ''Atropa'' (the belladonna genus). ''Atropa'' is named after the Greek Fate, Atropos, who cut the thread of life. This nomenclature reflects its toxicity and lethality. They are bicyclic organic nitrogen compounds (IUPAC nomenclature: 8-methyl-8-azabicyclo .2.1ctane), with the chemical formula of C₈H₁₅N. These alkaloids include, among others, atropine, cocaine, scopolamine, and hyoscyamine. They are found in various species, such as mandrake (''Mandragora officinarum'' and M. autumnalis ), black henbane or stinking nightshade (''Hyoscyamus niger''), belladonna (''Atropa belladonna''), jimson weed or devil's snare (''Datura stramonium'') and ''Brugmansia'' , as well as many others in the family Solanaceae. Pharmacologically, they are the most powerful known anticholinergics in existence, meaning they inhibit the neurological signals transmitted by the endogenous neurotransmitter, acetylcholine. More commonly, they can halt many types of allergic reactions. Symptoms of overdose may include dry mouth, dilated pupils, ataxia, urinary retention, hallucinations, convulsions, coma, and death. Atropine, a commonly used ophthalmological agent, dilates the pupils and thus facilitates examination of the interior of the eye. In fact, juice from the berries of ''A. belladonna'' were used by Italian courtesans during the Renaissance to exaggerate the size of their eyes by causing the dilation of their pupils ("bella donna" means "pretty woman" in Italian). Despite the extreme toxicity of the tropanes, they are useful drugs when administered in extremely small dosages. They can reverse cholinergic poisoning, which can be caused by overexposure to organophosphate insecticides and chemical warfare agents such as sarin

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