Nicotiana attenuata

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Nicotiana attenuata
Nicotiana attenuata USDA002 crop.jpg

Nicotiana attenuata

Systematics
Euasterids I
Order : Nightshade (Solanales)
Family : Nightshade family (Solanaceae)
Genre : Tobacco ( Nicotiana )
Section : Nicotiana sect. Petunioides
Type : Nicotiana attenuata
Scientific name
Nicotiana attenuata
Torr. ex S. Watson

Nicotiana attenuata is a plant type from the genus tobacco ( Nicotiana ). Within the genus it is classified in the section Petunioides , the closest related species is Nicotiana acuminata . The annual plant, which can growup to 150 centimeters high,is noticeably covered with glandular planthairs( trichomes ). The flowers usually open at night, the crown is narrow, funnel-shaped and colored white. The species is thusadaptedto pollination by nocturnal butterflies .

The range of the species is in the southwest of the United States . There it is mainly to be found in locations where forest fires recently occurred. Due to its adaptation to this special habitat, among other things, the plant serves as a model organism for researching the relationship between plants and their environment. The plants were used as smoke tobacco by some Indian peoples, and archaeological evidence of such use can be dated to around AD 650.

description

Vegetative characteristics

Deciduous leaves of Nicotiana attenuata : Larger leaves form a rosette on the ground, the leaves on the stem become significantly smaller.

Nicotiana attenuata is an upright, simple or branched, strong smelling annual plant that is 50 to 150 centimeters high. If it is branched, the middle stem is usually strongest. The leaves located near the ground form a rosette , they are slightly fleshy and 5 to 10 centimeters long. They are elliptical, egg-shaped, elliptical or elongated elliptically. Towards the front they are blunt or rarely also pointed. The leaf stalks are usually about half as long as the leaf blades . At the age of two to six weeks, the stem axis begins to lengthen. The foliage leaves formed above the basal rosette have increasingly shorter stems, the leaf blades become ever narrower, so that their shape becomes lanceolate to linear-lanceolate, towards the front they become more and more pointed.

The plant has glandular hairs with two different types of trichomes : a longer, stalked type, and a slightly shorter, also stalked type. The first type occurs evenly on both sides of the leaves, but the second type can usually only be found along the leaf axis. In old age, the plant can become bald. The trichomes have a swollen base that looks like drops of liquid on living plants, but in herbal specimens it collapses into a fine crater-shaped elevation.

Inflorescences and flowers

View into the crown of a flower of Nicotiana attenuata

The inflorescences are short cluster-shaped or narrow panicle-shaped , they are accompanied by linear, more or less straight bracts that are shorter than 30 millimeters. The flower stalks are initially 2 to 4 millimeters long, later they lengthen to 4 to 7 millimeters. The flowers have calyxes consisting of five fused sepals with a length of 7 to 10 millimeters. There are noticeable trichomes on the outside, which also have a thickened base. The calyx tube is covered with five triangular, unevenly shaped lobes, the larger ones reach a length of about 1.5 to 4.5 millimeters.

The crown consists of five fused petals, it is narrowly funnel-shaped and colored white. The corolla tube reaches a length of 20 to 27 (rarely up to 32) millimeters. It divides into a narrow area at the base with a length of 5 millimeters and a diameter of 1.5 to 2 millimeters, as well as a crown throat that is not quite double the diameter. This crown throat is almost cylindrical, upwards it is shifted slightly asymmetrically. The outside is finely downy, pale green and tinged with pink. The white colored coronet measures 4 to 6 millimeters in diameter and is only covered with slightly pronounced corolla lobes. These are 2 to 3 millimeters long, blunt or only rarely pointed. The top three are slightly bent back, the bottom two slightly ascending. The five stamens start at the base of the crown throat, the stamens are finely downy hairy and slightly curved directly above this point of attachment. The length of the stamens is different: In one pair, the anthers reach the opening of the corolla tube, the second pair is shorter and already clearly enclosed by the corolla tube and the fifth stamen is even shorter.

The flowers usually open in the evening. Occasionally, however, flowers are formed that open in the morning. These are significantly smaller, the diameter of the crown is only about a third of the flowers that open in the evening.

Fruits and seeds

The fruit is an 8 to 12 millimeter long, egg-shaped capsule with a pointed tip , at the tip of which four chambers are formed and which ripens about 16 days after the flower has been fertilized. It contains between 10 and 300 seeds that are more or less kidney-shaped or angularly kidney-shaped and up to 0.7 millimeters long. They have a matt gray-brown, ribbed, reticulated surface. The embryo is semicircular.

Distribution and locations

The species occurs in the southwest of North America . The northernmost distribution is around 50 ° north latitude in British Columbia ( Canada ), in the south it extends to 29 ° north latitude in Mexico . In the west it can be found in California and on the island of Guadalupe in front of Baja California , in the east the distribution area extends over Montana , Wyoming , Colorado and New Mexico into western Sonora . Within this area, Nicotiana attenuata is particularly common in the vegetation of the Great Basin , which corresponds to the area from southern Oregon and Idaho , east of the Sierra Nevada to the Owens Valley , along Nevada and as far as New Mexico. The species grows in runoff, on sandy slopes, roadsides and fields.

ecology

Dormancy and germination after fires

The plants usually only appear a few (one to three) years after fires in sagebrush and pinyon pine / juniper forests, only individual populations survive for several vegetation seasons in runoff and as weeds on newly built roads. After a fire in an up to 150 year old juniper stand in Utah in 1994 on an area of ​​more than 800 hectares, more than 10,000 individual plants of Nicotiana attenuata were found in the following year . Since the nearest population is over 8 kilometers away and no mechanisms of propagation of the seeds are known, it is assumed that the plants grew from seeds that have survived a dormancy (seed dormancy ) of over 100 years . This dormancy is controlled by a combination of positive and negative signals: The germination is prevented by substances that arise when plants - potentially competing for nutrients - rotting, whereby the actual germination capacity of the seeds is not impaired; Germination is promoted by substances that arise when cellulose is burned. One advantage that the plant has as a result is the disappearance of potential competitors; In addition, the increased ammonia concentration that is present in the ground after fires can be used to synthesize nicotine .

In experiments in which potted Nicotiana attenuata plants were placed on the one hand at juniper sites that had recently burned down and on the other at sites that had not burned down, it was possible to demonstrate that the amount of leaf area eaten by herbivores at the former locations was one to Was 20 times less. The adaptation to these special locations is therefore to be seen as a protection against predators.

Pollinators

The pollinators of Nicotiana attenuata include hawks of the genus Manduca (especially the tobacco hawks ( Manduca sexta ) and Manduca quinquemaculatus ), as well as hummingbirds , especially the species Archilochus alexandri , but also the red-backed cinnamon ( Selasphorus rufus ). Both groups of pollinators visit the flowers to collect the sugary nectar . In addition to sugar, this reward provided by the plant contains a large number of volatile organic compounds that affect the behavior of pollinators via smell and taste. Experiments have shown that benzyl acetone is the most important component of nectar in order to attract pollinators, but nicotine is repulsive and reduces the amount of nectar ingested by pollinators. The presence of nicotine in the nectar of the plant was initially mostly seen as a side effect of the accumulation of the substance in the leaves to ward off predators. However, this also increases the number of flowers visited by a pollinator, which in turn leads to a higher outcrossing rate and thus to a lower inbreeding depression of the population.

Defense against predators

Spodoptera exigua caterpillar on a leaf of Nicotiana attenuata .

The natural enemies of Nicotiana attenuata are mainly caterpillars from various butterflies. On the one hand, there are butterfly species that specialize in tobacco species, such as the tobacco hawk ( Manduca sexta ), but there are also non-specialized species such as Spodoptera exigua and Spodoptera littoralis . Mainly the leaves are eaten, to a lesser extent also the flowers and fruits. Damage is also caused by vertebrates , which usually eat the plant above the rosette. Erdhörnchen species of the genera of the observed ground squirrel ( spermophilus ) and antelope squirrel ( Ammospermophilus ), the California donkey rabbit ( Lepus californicus ), and the desert cottontail ( Sylvilagus audubonii ).

The nicotine enriched in the plant , which acts as a nerve poison , is considered to be the most effective defense against most unspecialized predators . If the plant is infested, the nicotine production increases to about two to four times (in individual cases more than 14 times) in order to ward off the predators. The concentration of nicotine in the trichomes of the calyx is particularly high ; a single plant hair can contain between 1.3 and 3.6 micrograms of the alkaloid.

As a side effect of nicotine enrichment, the plant can only produce a smaller amount of seeds, but these losses are less for the plant than the loss of seeds if there is no response to the infestation. Even the caterpillars of the specialized tobacco hawk grow more slowly if they eat leaves that contain nicotine, but the nicotine ingested serves as protection against the caterpillars' enemies. If the nicotine production in the plants is suppressed, the infestation increases with a large number of insects, which otherwise only play a less important role as predators. These include, for example, the owl butterfly Spodoptera exigua , representatives of the locust genus Trimerotropis and the leaf beetle Epitrix hirtipennis .

It could be shown that the oral excretions of the caterpillars of the tobacco hawk change the production of volatile constituents of the leaf green. More ( Z ) -isomers than ( E ) -isomers occur on purely mechanically injured leaves , while the ratio is more and more balanced in leaves that are attacked by tobacco hawk caterpillars. This change serves as a signal to predatory species of the Geocoris genus from the Geocoridae family that the plants are prey in the form of eggs and larvae of the tobacco hawk.

Change of preferred pollinators

The moths of the genus Manduca are the primary pollinators of the species. Since the adult moths are important for the survival of the species, but the caterpillars threaten the plants as predators at the same time, a regulatory process is developed in Nicotiana attenuata , with which an excessive infestation of caterpillars should be prevented. If the caterpillars feed on the plants, the production of the plant hormone jasmonic acid is triggered in response to the oral excretions and regurgitants . This causes the plant to change the flowering rhythm: if the flowers normally open in the evening hours (between 6 and 10 p.m.) to be pollinated by moths at night, more and more flowers are formed when there is a high infestation of caterpillars open in the morning (between 6 and 10 a.m.). These flowers are smaller, their scent contains less benzyl acetone and their nectar has a lower concentration of sugar. This adaptation of the flowers means that they are now mainly pollinated by hummingbirds . It is assumed that a complete adaptation to pollination by hummingbirds would be disadvantageous, since they cannot be lured over long distances by means of flower scents like moths and because the birds' nesting sites often not at the locations of the species, which are mostly overgrown after fires available.

Systematics

Within the genus Nicotiana , Nicotiana attenuata is classified in the Petunioides section . All species in the section are annual herbs with a chromosome number of n = 12 and a diploid chromosome set, most species are common in the southwest of the Andes . The closest related is Nicotiana attenuata to Nicotiana acuminata . Due to the high similarity and the fact that the distribution areas are, in contrast, separated from each other, it is assumed that Nicotiana attenuata reached North America relatively late through the distribution of seeds over long distances. It is also assumed that the allopolyploid section Polydicliae arose from the ancestors of Nicotiana obtusifolia as the male parent species and the ancestors of Nicotiana attenuata as the female parent species about 1 million years ago . In 2010, two artificially generated hybrids were described that are intended to simulate this process: Nicotiana × mierata was generated with Nicotiana miersii as the second parent species and Nicotiana × obtusiata with Nicotiana obtusifolia .

use

The use of Nicotiana attenuata as smoking tobacco has been documented by some Indian tribes in the area of ​​distribution, including the Washoe , Cahuilla , Kumeyaay , Zuñi , Ute , Gosiute and the northern Blackfoot . The species is often called "coyote tobacco" in this context. Some of the plants were cultivated near the settlement sites. During excavations of historical settlement sites from the Basketmaker III epoch (around 650 AD) in northern Arizona , small bundles were found that contained, among other things, plant remains that were identified as Nicotiana attenuata . These plants were probably used for medicinal purposes, and it has also been proven that this tobacco was smoked in pipes.

In the ethnobotanical literature of the 20th century there is a large number of other references of the species. These include the use against nosebleeds , colds , hives , measles , tuberculosis , snakebites, various pains such as headaches , toothaches or rheumatism and against infestation by various worms . The types of documented applications range from smoking the leaves to rubbing them with a brew cooked from the plants to applying chewed leaves to parts of the body to be healed. Used when washing hair, the plant is said to help against dandruff and hair loss .

Research history

Illustration of Nicotiana attenuata and Nicotiana bigelovii (valid name: Nicotiana quadrivalvis ) from the first description by Sereno Watson (1871)

The first description of Nicotiana attenuata , which is valid according to the rules of the International Code of Nomenclature for Algae, Fungi and Plants (ICBN) , was written in 1871 by Sereno Watson in the fifth volume of the series "United States Geological Exploration of the Fortieth Parallel". There he gives as the author of the name John Torrey , as the source of the name he mentions "in Herb." (In the herbarium ). According to Article 32.1 ICBN, a validly described taxon must contain a description or diagnosis, which is not given in a herbarium. The resulting author quote is Torr. ex S. Watson . The fact that the name was already used by Ernst Gottlieb von Steudel in 1821 is irrelevant according to Article 34.1 ICBN, as it is a nomen nudum . The holotype is a herbarium specimen from John Torrey with specimen number Torrey 354 , which is in the herbarium of the New York Botanical Garden . One isotype belongs to the collection of the Asa Gray Herbarium at Harvard University . The evidence probably comes from an adult, but not very old individual: the native rosette of leaves is missing, and the inflorescences are usually more pronounced on older plants.

Descriptions of the species have been published in various flora works , including in "Synopsis of the Flora of Colorado" (1874), "Synoptical Flora of North America" ​​(1878), "A popular California Flora" (1882), "A Flora of western middle California "(1901)," Flora of Colorado "(1905)," Elemental Flora of the Northwest "(1914)," Flora of southeastern Washington and adjacent Idaho "(1914)," Flora of New Mexico "(1914), "Flora of southern British Columbia and Vancouver Island" (1915), "Flora of the Rocky Mountains and adjacent plains" (1917), "A Flora of California" (1943) and "An illustrated flora of the Pacific States" (1951) .

The work of Thomas Harper Goodspeed , who summarized the results of his work in 1954 in the monograph The Genus Nicotiana , made a major contribution to the research of the entire genus Nicotiana . This book and the systematics used in it and the taxonomic treatises have long been considered a reference to the genus. The division into subgenera and sections has been used in both botanical and agricultural literature. Nicotiana attenuata is assigned to the subgenus Petunioides and within this subgenus the section Acuminatae . The assignment to the sections could in most cases be confirmed by molecular biological investigations, but the section name Acuminatae used by Goodspeed is invalid, the older name Petunioides has priority . These molecular biological investigations were used to research the phylogenetic relationships both within the genus Nicotiana and the entire nightshade family . Nicotiana attenuata was examined for the first time by Richard Olmstead and Jeffery Palmer with these methods; their results of the comparison of the restriction enzymes of the DNA of the chloroplasts were published in 1991. Furthermore, the genes ndhF and matK , as well as the DNA spacers trnL-F and trnS-G, were sequenced in various studies .

Since the late 1980s, Nicotiana attenuata has been increasingly used as a model organism for researching the interaction between plants and their environment. Above all, due to its specialization in living in an ecological niche - the habitat in burned-down bushes and trees - the species is a suitable object of investigation. The main reason for this development is the work of Ian T. Baldwin , who initially began research at the State University of New York . In 1995, the Max Planck Society gave him the opportunity to take up a position as founding director of the Max Planck Institute for Chemical Ecology in Jena and to continue his research there. In addition to the facilities and greenhouses in Jena, the institute also operates a test station in Utah in the natural range of the species in order to carry out field tests there.

literature

  • Thomas Harper Goodspeed: The Genus Nicotiana: Origins, Relationships and Evolution of its Species in the Light of their Distribution, Morphology and Cytogenics. 1954. (Reprinted by AJ Reprints Agency, New Delhi 1982)

Web links

Commons : Nicotiana attenuata  - collection of images, videos and audio files

proof

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  2. ^ A b c Ian T. Baldwin, Thomas E. Withoutiss: Alkaloidal Responses to Damage in Nicotiana Native to North America. In: Journal of Chemical Ecology. Volume 19, Number 6, 1993, pp. 1143-1153. doi: 10.1007 / BF00987376
  3. ↑ a b c d e f g TH Goodspeed, H.-M. Wheeler, PC Hutchinson: Nicotiana attenuata, Taxonomic Treatment In: Thomas Harper Goodspeed (Ed.): The Genus Nicotiana: Origins, Relationships and Evolution of its Species in the Light of their Distribution, Morphology and Cytogenics. 1954. Reprinted from AJ Reprints Agency, New Delhi 1982, pp. 427-430.
  4. ↑ Alexander Weinhold et al: Phaseoloidin, a Homogentisic Acid Glucoside from Nicotiana Attenuata Trichomes, Contributes to the Plant's Resistance against Lepidopteran Herbivores. In: Journal of Chemical Ecology. Volume 37, Number 10, 2011, pp. 1091-1098. doi: 10.1007 / s10886-011-0012-7
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  7. ^ A b Danny Kessler, Celia Diezel, Ian T. Baldwin: Changing Pollinators as a Means of Escaping Herbivores. In: Current Biology. Volume 30, February 2010, pp. 237-242. doi: 10.1016 / j.cub.2009.11.071
  8. ↑ a b Michael Euler, Ian T. Baldwin: The chemistry of defense and apparency in the corollas of Nicotiana attenuata. In: Oecologia. Volume 107, Number 1, 1996, pp. 102-112. doi: 10.1007 / BF00582240
  9. ↑ Philip V. Wells: An Ecological Investigation of two Desert Tobaccos. In: Ecology. Volume 40, Number 4, October 1959, pp. 626-644. doi: 10.2307 / 1929816
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  17. ^ Silke Allmann, Ian T. Baldwin: Insects Betray Themselves in Nature to Predators by Rapid Isomerization of Green Leaf Volatiles. In: Science. Volume 329, August 27, 2010, pp. 1075-1078. doi: 10.1126 / science.1191634
  18. ↑ Mario Kallenbach, Fiammetta Alagna, Ian T. Baldwin, Gustavo Bonaventure: Nicotiana attenuata SIPK, WIPK, NPR1, and Fatty Acid-Amino Acid Conjugates Participate in the Induction of Jasmonic Acid Biosynthesis by Affecting Early Enzymatic Steps in the Pathway. In: Plant Physiology. Volume 152, Number 1, January 2010, pp. 96-106. doi: 10.1104 / pp.109.149013
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  21. ↑ K. Yoong Lim et al .: Sequence of events leading to near-complete genome turnover in allopolyploid Nicotiana within five million years. In: New Phytologist. Volume 175, Issue 4, 2007. doi: 10.1111 / j.1469-8137.2007.02121.x
  22. ↑ Ales Kovarik et al: Evolution of rDNA in Nicotiana Allopolyploids: A Potential Link between rDNA Homogenization and Epigenetics. In: Annals of Botany. Volume 101, Issue 6, 2008, pp. 815-823. doi: 10.1093 / aob / mcn019
  23. ↑ S. Anssour et al: Phenotypic, genetic and genomic consequences of natural and synthetic polyploidization of Nicotiana attenuata and Nicotiana obtusifolia. In: Annals of Botany. Volume 103, 2009, pp. 1207-1217. doi: 10.1093 / aob / mcp058
  24. ↑ Tamara Krügel: Nicotiana × mierata and N. × obtusiata - two new synthetic hybrids. In: Haussknechtia. Announcements of the Thuringian Botanical Society Jena. Issue 12, 2010, pp. 23-26.
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  43. ↑ a b Vicente F. Garcia, Richard G. Olmstead: Phylogenetics of Tribe Anthocercideae (Solanaceae) Based on ndhF and trnL / F Sequence Data. In: Systematic Botany. Volume 28, Number 3, 2003, pp. 609-615. doi: 10.1043 / 02-52.1
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