SOLANACEAE: CHARACTERISTICS, HABITAT, TOXICITY, ALLERGIES, CULTIVATION - SCIENCE - 2024

The Solanaceae are a taxonomic family of angiosperms herbaceous or shrubby Solanales belonging to the class Magnoliopsida order. This group is made up of approximately 95 genera and 2,500 species with a wide distribution, both in tropical and warm regions and in temperate and cold regions.

Its largest center of biodiversity is found in South and Central America, this region being the center of origin for most of its clades. In fact, more than 65 genera and 1,575 species are native to tropical America, and from there they have spread throughout Eurasia, Africa, and Australia.

Solanaceae. Source: pixabay.com

This family includes species of food interest such as the genus Capsicum (chili peppers or peppers), Solanum tuberosum (potato), Solanum lycopersicum (tomato) or Solanum melongena (aubergine). Also, species for ornamental use, such as the genera Datura, Salpiglossis, Schizanthus and Petunia.

Other species, such as Withania somnífera (bufera) have medicinal use due to its antibiotic, anti-flu and energizing capacity. Nicotiana tabacum (tobacco) leaves contain nicotine, being the raw material for making cigarettes and cigars, and are also used as a pesticide or home remedy.

Some species contain significant amounts of alkaloids and nitrogenous compounds, such as atropine, nicotine or solanine, which in some cases are used as stimulants. However, its consumption can be toxic in people or animals, due to its psychotropic effect, which is why certain species are considered poisonous.

General characteristics

Appearance

These are herbaceous, shrub and arboreal plants, erect, creeping or climbing habits, annual, biennial or perennial cycle. Sympathetic growing branches covered with firm, stellate, or spiny bristles are common.

Leaves

The leaves are simple, occasionally compound, arranged alternately at the base of the plant and opposite at the top. The blade is herbaceous in consistency, leathery or transformed into spines, short petioles, but never sessile, little obvious veins and entire or lobed margins.

flowers

Hermaphroditic, dioecious, monoecious or andromonoic plants, actinomorphic or zygomorphic flowers, arranged solitary or in cymose, axillary or terminal inflorescences. The flowers are generally pentameric, with a corolla united at the base in a campanulate shape, a supero bilocular or multilocular ovary, alternate stamens and a terminal style.

Capsicum (chili peppers or peppers). Source: pixabay.com

Fruit

The fruit can be a berry, a septic capsule, never loculicidal or valve, or a drupe. The seeds are oily, have abundant endosperm, but not starchy, dicotyledons, and the embryo is straight or curved. Most are polyploid species.

Chemical composition

Solanaceae contain different types of secondary metabolites synthesized from amino acids or alkaloids with a more or less toxic effect. Among them are atropine, scopolamine, hyoscyamine or nicotine, common in species such as Atropa belladonna (belladonna), Datura stramonium (jimson), Hyoscyamus albus (henbane), Mandragora autumnalis (mandrake) and Nicotiana tabacum (tobacco).

Capsaicin is an oleoresin with an irritating effect that gives the fruits of the Capsicum genus a spicy flavor and aroma. Nicotine is an alkaloid with a stimulating effect and is the main organic compound present in the species Nicotiana tabacum (tobacco).

Solanine is a toxic glycoalkaloid with a bitter taste that is found naturally in the leaves, fruits and tubers of some nightshades, such as eggplant, potato and tomato. Atropine, scopolamine, and hyoscyamine are nervous system stimulating troan alkaloids, found in various species of nightshade.

Solanum tuberosum (potato). Source: pixabay.com

Taxonomy

- Kingdom: Plantae

- Phylum: Magnoliophyta

- Class: Magnoliopsida

- Order: Solanales

- Family: Solanaceae

Subfamilies

- Cestroideae (syn. Browallioideae)

- Goetzeoideae

- Petunioideae

- Schizanthoideae

- Schwenckioideae

- Nicotianoideae

- Solanoideae

Solanum lycopersicum (tomato). Source: pixabay.com

Habitat and distribution

Solanaceae are found in a great diversity of habitats, from tropical, dry and quality conditions, to temperate, humid and cold environments. They grow on fertile, loose and permeable soils, in montane rainforest ecosystems or dry forests, including desert environments and anthropized lands.

It is considered a cosmopolitan family, widely distributed in tropical, subtropical and temperate regions, with South America being its center of origin and dispersal. Most of the native species of South America are endemic, Africa and Australia are regions of great genetic diversity and it is cultivated commercially in Asia and Europe.

Solanum melongena (aubergine). Source: pixabay.com

Toxicity

The number of edible nightshades, such as chili or pepper, aubergine, potato and tomato are quite small. However, the amount of toxic nightshade, such as belladonna, henbane, thorn apple or mandrake is very numerous, their intake can even cause death.

Regular consumption of nightshade does not cause any adverse reactions in most people. However, particular health conditions such as autoimmune diseases, intestinal disorders or intolerance to certain alkaloids, can cause toxic reactions.

Scientific studies in mammals have linked the consumption of nightshades with joint pain and rheumatoid arthritis. Some nightshades have a high content of vitamin D ₃, whose synthesis generates metabolites that prevent the correct accumulation of calcium in the bones.

Petunia. Source: pixabay.com

For the case of people, this study is inconclusive. In humans, the synthesis of vitamin D _{3 is} not carried out in the same way as the mammals in the study.

However, the presence of certain alkaloids such as capsaicin (peppers), nicotine (tobacco), and solanine (potatoes) can cause dangerous reactions in some people. These substances are natural compounds that act as defense mechanisms against predators, but their consumption can cause pain, inflammation, spasms or muscle stiffness.

In fact, Solanaceae develop alkaloids as defense mechanisms, in poisonous species their concentration is so high that they can be fatal to people. In edible species, the stems and leaves have a low concentration, however, this small content can cause toxicity problems in sensitive people.

People with intestinal diseases, ulcerative colitis, sclerosis, celiac disease or Crohn's disease have a greater permeability of the intestine. The alkaloids present in nightshades easily penetrate the walls of the intestine causing toxic reactions.

Atropa belladonna (belladonna). Source: pixabay.com

Allergies

The stems and leaves of certain nightshades have allergic effects on certain people. Ripe fruits or berries, as in the case of aubergines and tomatoes, lose their toxicity when ripe, although it persists in plants such as dulcamara and black solano.

Most nightshade poisoning occurs in young children who consume the fruits of dulcamara or black solano due to their attractive appearance and coloration. The first symptoms of intoxication or allergies appear during the first half hour, the patient experiences nausea, vomiting, intestinal pain and diarrhea.

In more severe cases, there is a skin redness, dryness of the oral mucosa, motor lack of coordination, weakness and alteration of the nervous system. In extreme cases, seizures, low blood pressure, and respiratory depression can occur. Its treatment consists of the application of anticholinergic drugs, such as physostigmine or eserine.

Datura stramonium (Jimson weed). Source: pixabay.com

Culture

Requirements

Solanaceae are plants that require full sun exposure, preferring direct sun radiation to favor the pigmentation of their fruits. They are plants of tropical origin, so they thrive in environments with temperatures above 12-15 ºC.

They should be located in cool and well ventilated areas, they are sensitive to low temperatures so they should be protected from cold air currents. During the warm season it is advisable to carry out frequent nebulisations to maintain the high humidity, essential for the flowering and fruiting processes.

Nicotiana tabacum (tobacco). Source: pixabay.com

Spread

Most of the species in the Solanaceae family are propagated by means of seeds. In the case of edible tubers such as Solanum tuberosum, the propagation is carried out vegetatively.

In the case of sowing by seeds, the establishment of the crop is carried out on germination trays at the beginning of spring. The seeds are broadcast on a fertile substrate based on coarse sand and composted material, trying to cover with a thin layer of substrate.

The germination trays are kept in partial shade, with frequent humidity and a constant temperature between 18-22 ºC. Depending on the species, the seeds begin the germination process 25-35 days after sowing.

When the seedlings have reached 8-10 cm in height and have 4-6 true leaves, 2-3 hours of direct light are procured daily for conditioning before transplanting. Once they are strong and vigorous, they are transplanted to the final place, carrying out the appropriate agronomic management according to each species.

Mandragora autumnalis (mandrake). Source: pixabay.com

Care

- Solanaceae require abundant moisture throughout the productive period, ensuring that the land remains humid without causing waterlogging.

- After fruiting, the frequency of irrigation should be reduced to avoid the appearance of some type of fungal diseases, trying not to let the ground dry out.

- They grow on loamy, loose, well-drained and fertile soils. When establishing the seedbed, it is recommended to use a substrate made of compost, peat and coarse sand in equal parts.

- It is appropriate to make amendments to organic fertilizer every 15-20 days throughout the production cycle. Mineral fertilizers are effective in promoting the flowering and fruiting process.

- Some species with a biennial or perennial cycle require maintenance pruning at the end of the first cycle, carrying out a drastic pruning that favors the proliferation of new shoots.

- Likewise, depending on the species, the practice of topping can be carried out. This consists of eliminating the vegetative tips in order to favor the growth of the lateral shoots, flowering and fruiting.

References

1. Bohs L. & Olmstead RG (1997) Phylogenetic relationships in Solanum (Solanaceae) based on ndhF sequences. Syst. Bot. 22: 5-17.
2. Díez, V. (2015) Solanaceae and Autoimmune Diseases. Recovered at: paleomoderna.com
3. García, C. (2011). Characterization of local varieties of Solanaceae (Graduate Thesis). Escola Agraria de Manresa, Barcelona, ​​Spain.
4. Gutiérrez Jiménez, J., Luna-Cazáres, LM & Verdugo Valdez, AG (2008) Uses of Solanaceae. Plant genetic resources and sustainability in Chiapas. ISBN: 978-968-5149-81-5
5. Mendivil Navarro, J. (2020) Solanaceae Family. Recovered in: Naturalezadearagon.com
6. Portillo., G. (2019) Properties and benefits of nightshades. Gardening On. Recovered in: jardineriaon.com
7. Solanaceae Juss. (2017) Laboratory of Vascular Plant Systematics. Recovered at: thecompositaehut.com
8. Solanaceae. (2020). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org