Populus trichocarpa
Encyclopedia
Populus trichocarpa is a deciduous
broadleaf tree
species native to western North America
. It is used for timber
, and is notable as a model organism
in plant biology. Its full genome
sequence was published in 2006. It is the first tree species to be sequenced.
species in the Americas. It is normally fairly short-lived, but some trees may live for up to 400 years (Forbes 2006). A cottonwood discovered in Haines, Alaska
set the national record at 101 ft (30.8 m) tall and 32.5 ft (9.9 m) around.
The bark
is grey and covered with lenticel
s, becoming thick and deeply fissured on old trees. The bark can become hard enough to cause sparks when cut with a chainsaw. The stem is grey in the older parts and light brown in younger parts. The crown
is usually roughly conical and quite dense. In large trees the lower branches droop downwards. Spur shoots are common. The wood
has a light coloring and a straight grain.
The leaves
are 7–20 cm long with a glossy dark green upper side and glaucous light grey-green underside; larger leaves, up to 30 cm long, may be produced on stump sprouts and very vigorous young trees. The leaves are alternate, elliptic with a crenate margin and an acute tip, and reticulate venation (see leaf terminology). The petiole is reddish. The bud
s are conical, long, narrow and sticky, with a strong balsam scent in spring when they open.
P. trichocarpa has an extensive and aggressive root system, which can invade and damage drainage systems. Sometimes the roots can even damage the foundations of buildings by drying out the soil.
P. trichocarpa is normally dioecious
; male
and female
catkin
s are borne on separate trees. The species reaches flowering age at about 10 years. Flowers may appear in early March to late May in Washington and Oregon
, and sometimes as late as mid-June in northern and interior British Columbia
, Idaho
, and Montana
. Staminate
catkin
s contain 30 to 60 stamen
s, elongate to 2 to 3 cm, and are deciduous
. Pistillate catkin
s at maturity are 8 to 20 cm long with rotund-ovate
, three carpellate subsessile fruits 5 to 8 mm long. Each capsule contains many minute seed
s with long, white cottony hairs.
Seed Production and Dissemination
The seed ripens and is disseminated by late May to late June in Oregon
and Washington, but frequently not until mid-July in Idaho
and Montana
. Abundant seed crops are usually produced every year. Attached to its cotton, the seed is light and buoyant and can be transported long distances by wind and water. Although highly viable, longevity of P. trichocarpa seed under natural conditions may be as short as 2 weeks to a month. This can be increased with cold storage.
Seedling development
Moist seedbeds are essential for high germination, and seedling survival depends on continuously favorable conditions during the first month. Wet bottom lands of rivers and major streams frequently provide such conditions, particularly where bare soil has been exposed or new soil laid down. Germination is epigeal
. P. trichocarpa seedlings do not usually become established in abundance after logging
unless special measures are taken to prepare the bare, moist seedbeds required for initial establishment. Where seedlings become established in great numbers, they thin out naturally by age 5 because the weaker seedlings of this shade-intolerant species
are suppressed.
Vegetative reproduction
:
Due to its high levels of rooting hormones, P. trichocarpa sprouts readily. After logging
operations, it sometimes regenerates naturally from rooting of partially buried fragments of branches or from stumps. Sprouting from roots also occurs. The species also has the ability to abscise shoots complete with green leaves. These shoots drop to the ground and may root where they fall or may be dispersed by water transport. In some situations, abscission may be one means of colonizing exposed sandbars.
. It extends northeast from Kodiak Island
along Cook Inlet
to latitude
62° 30° N., then southeast in southeast Alaska
and British Columbia
to the forested areas of Washington and Oregon
, to the mountains in southern California
and northern Baja California
(lat. 31° N.). It is also found inland, generally on the west side of the Rocky Mountains
, in British Columbia
, western Alberta
, western Montana
, and northern Idaho
. Scattered small populations have been noted in southeastern Alberta
, eastern Montana
, western North Dakota
, western Wyoming
, Utah
, and Nevada
. It grows up to elevations of 2100 m.
Populus trichocarpa has been one of the most successful introduction of trees to the otherwise more or less treeless Faroe Islands
Branches can be added to potted plants to stimulate rooting.
For these reasons the species has been extensively studied. Its genome
sequence was published in 2006 (see "Genome" below). More than 121 000 expressed sequence tag
s (ESTs) have been sequenced
from it. The wide range of topics studied by using P. trichocarpa include the effects of ethylene
, lignin
biosynthesis
, drought tolerance and wood
formation.
fibres which are used in the production of high-quality book and magazine paper
. The wood is also excellent for production of plywood
. Living tree
s are used as windbreak
s.
P. trichocarpa grows very quickly; trees in plantation
s in Great Britain have reached 18 m (59.1 ft) tall in 11 years, and 34 m (111.5 ft) tall in 28 years (Mitchell 1996). It can reach suitable size for pulp
production in 10–15 years and about 25 years for timber
production.
Commercial extracts are produced from the fragrant buds for use as a perfume in medicines and cosmetics.
'P. trichocarpa contains salicin, and has been used medicinally as an antipyretic
, analgesic
and to control inflammation
.
specimen "Nisqually-1", named after the Nisqually River
in the Washington state in the USA, where the specimen was collected. The sequencing
was performed at the Joint Genome Institute
by using the shotgun
method. The depth of the sequencing was approximately 7.5 x (meaning that each base pair
was sequenced
on average 7.5 times). Genome annotation was done primarily by the Joint Genome Institute
, the Oak Ridge National Laboratory
, the Umeå Plant Science Centre and Genome Canada.
Prior to the publication of P. trichocarpa genome
the only available plant genomes were those of thale cress
and rice
, both of which are herbaceous
. P. trichocarpa is the first woody plant genome
to be sequenced. Considering the economic importance of wood
and wood products, the availability of a tree genome
was necessary. The sequence also allows evolutionary comparisons and the elucidation of basic molecular differences between herbaceous
and woody plants.
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
broadleaf tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
species native to western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is used for timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
, and is notable as a model organism
Model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. Model organisms are in vivo models and are widely used to...
in plant biology. Its full genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
sequence was published in 2006. It is the first tree species to be sequenced.
Description
It is a large tree, growing to a height of 30–50 m and a trunk diameter of over 2 m, which makes it the largest poplarPoplar
Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar , aspen, and cottonwood....
species in the Americas. It is normally fairly short-lived, but some trees may live for up to 400 years (Forbes 2006). A cottonwood discovered in Haines, Alaska
Haines, Alaska
Haines is a census-designated place in Haines Borough, Alaska, United States. As of the 2000 census, the population of the area was 1,811. Haines was formerly a city but no longer has a municipal government...
set the national record at 101 ft (30.8 m) tall and 32.5 ft (9.9 m) around.
The bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
is grey and covered with lenticel
Lenticel
A lenticel is an airy aggregation of cells within the structural surfaces of the stems, roots, and other parts of vascular plants. It functions as a pore, providing a medium for the direct exchange of gasses between the internal tissues and atmosphere, thereby bypassing the periderm, which would...
s, becoming thick and deeply fissured on old trees. The bark can become hard enough to cause sparks when cut with a chainsaw. The stem is grey in the older parts and light brown in younger parts. The crown
Crown (botany)
The crown of a plant refers to the totality of the plant's aboveground parts, including stems, leaves, and reproductive structures. A plant canopy consists of one or more plant crowns growing in a given area....
is usually roughly conical and quite dense. In large trees the lower branches droop downwards. Spur shoots are common. The wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
has a light coloring and a straight grain.
The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are 7–20 cm long with a glossy dark green upper side and glaucous light grey-green underside; larger leaves, up to 30 cm long, may be produced on stump sprouts and very vigorous young trees. The leaves are alternate, elliptic with a crenate margin and an acute tip, and reticulate venation (see leaf terminology). The petiole is reddish. The bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s are conical, long, narrow and sticky, with a strong balsam scent in spring when they open.
P. trichocarpa has an extensive and aggressive root system, which can invade and damage drainage systems. Sometimes the roots can even damage the foundations of buildings by drying out the soil.
Reproduction
Flowering and FruitingDioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...
; male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
and female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
catkin
Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
s are borne on separate trees. The species reaches flowering age at about 10 years. Flowers may appear in early March to late May in Washington and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, and sometimes as late as mid-June in northern and interior British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. Staminate
Stamen
The stamen is the pollen producing reproductive organ of a flower...
catkin
Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
s contain 30 to 60 stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s, elongate to 2 to 3 cm, and are deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
. Pistillate catkin
Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
s at maturity are 8 to 20 cm long with rotund-ovate
Ovule
Ovule means "small egg". In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integument forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center...
, three carpellate subsessile fruits 5 to 8 mm long. Each capsule contains many minute seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s with long, white cottony hairs.
Seed Production and Dissemination
The seed ripens and is disseminated by late May to late June in Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
and Washington, but frequently not until mid-July in Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
and Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
. Abundant seed crops are usually produced every year. Attached to its cotton, the seed is light and buoyant and can be transported long distances by wind and water. Although highly viable, longevity of P. trichocarpa seed under natural conditions may be as short as 2 weeks to a month. This can be increased with cold storage.
Seedling development
Moist seedbeds are essential for high germination, and seedling survival depends on continuously favorable conditions during the first month. Wet bottom lands of rivers and major streams frequently provide such conditions, particularly where bare soil has been exposed or new soil laid down. Germination is epigeal
Epigeal
Epigeal, epigean, epigeic and epigeous are biological terms describing an organism's activity above the soil surface.In botany, a seed is described as epigeal when the cotyledons of the germinating seed expand, throw off the seed shell and become photosynthetic above the ground...
. P. trichocarpa seedlings do not usually become established in abundance after logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
unless special measures are taken to prepare the bare, moist seedbeds required for initial establishment. Where seedlings become established in great numbers, they thin out naturally by age 5 because the weaker seedlings of this shade-intolerant species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are suppressed.
Vegetative reproduction
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
:
Due to its high levels of rooting hormones, P. trichocarpa sprouts readily. After logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
operations, it sometimes regenerates naturally from rooting of partially buried fragments of branches or from stumps. Sprouting from roots also occurs. The species also has the ability to abscise shoots complete with green leaves. These shoots drop to the ground and may root where they fall or may be dispersed by water transport. In some situations, abscission may be one means of colonizing exposed sandbars.
Distribution
The native range of P. trichocarpa covers large sections of western North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It extends northeast from Kodiak Island
Kodiak Island
Kodiak Island is a large island on the south coast of the U.S. state of Alaska, separated from the Alaska mainland by the Shelikof Strait. The largest island in the Kodiak Archipelago, Kodiak Island is the second largest island in the United States and the 80th largest island in the world, with an...
along Cook Inlet
Cook Inlet
Cook Inlet stretches from the Gulf of Alaska to Anchorage in south-central Alaska. Cook Inlet branches into the Knik Arm and Turnagain Arm at its northern end, almost surrounding Anchorage....
to latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
62° 30° N., then southeast in southeast Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
and British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
to the forested areas of Washington and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, to the mountains in southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and northern Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
(lat. 31° N.). It is also found inland, generally on the west side of the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
, in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, western Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, western Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, and northern Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
. Scattered small populations have been noted in southeastern Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
, eastern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, western North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
, western Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, and Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
. It grows up to elevations of 2100 m.
Populus trichocarpa has been one of the most successful introduction of trees to the otherwise more or less treeless Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
Cultivation
It is also grown as an ornamental tree, valued for its fast growth and scented foliage in spring, detectable from over 100 m distance. The roots are however invasive, and it can damage the foundations of buildings on shrinkable clay soils if planted nearby (Mitchel 1996).Branches can be added to potted plants to stimulate rooting.
Use as a model species
P. trichocarpa has several qualities which makes it a good model species for trees:- Model genome size (although significantly larger than the other model plant, Arabidopsis thalianaArabidopsis thalianaArabidopsis thaliana is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, arabidopsis is popular as a model organism in plant biology and genetics...
) - Rapid growth (for a tree)
- Reaches reproductive maturity 4–6 years
- Economically important
- It represents a phenotypicallyPhenotypeA phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
diverse genus
For these reasons the species has been extensively studied. Its genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
sequence was published in 2006 (see "Genome" below). More than 121 000 expressed sequence tag
Expressed sequence tag
An expressed sequence tag or EST is a short sub-sequence of a cDNA sequence. They may be used to identify gene transcripts, and are instrumental in gene discovery and gene sequence determination. The identification of ESTs has proceeded rapidly, with approximately 65.9 million ESTs now available in...
s (ESTs) have been sequenced
DNA sequencing
DNA sequencing includes several methods and technologies that are used for determining the order of the nucleotide bases—adenine, guanine, cytosine, and thymine—in a molecule of DNA....
from it. The wide range of topics studied by using P. trichocarpa include the effects of ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
, lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
, drought tolerance and wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
formation.
Lumber
P. trichocarpa wood is light-weight and although not particularly strong, is strong for its weight. The wood material has short, fine celluloseCellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
fibres which are used in the production of high-quality book and magazine paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
. The wood is also excellent for production of plywood
Plywood
Plywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...
. Living tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s are used as windbreak
Windbreak
A windbreak or shelterbelt is a plantation usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted around the edges of fields on farms. If designed properly, windbreaks around a...
s.
P. trichocarpa grows very quickly; trees in plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...
s in Great Britain have reached 18 m (59.1 ft) tall in 11 years, and 34 m (111.5 ft) tall in 28 years (Mitchell 1996). It can reach suitable size for pulp
Wood pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
production in 10–15 years and about 25 years for timber
Timber
Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...
production.
Medicinal
Native American tribes in the Pacific Northwest used P. trichocarpa for a variety of purposes. The inner bark was sometimes eaten but most of its uses were medicinal or practical. Because of its salicin content it was often used raw or in salves to treat a number of ailments including baldness, tuberculosis, rheumatism, and treating wounds. The wood, roots and bark were used for firewood, canoe making, rope, fish traps, baskets and structures. The gum-like sap was even used as a glue or as waterproofing.Commercial extracts are produced from the fragrant buds for use as a perfume in medicines and cosmetics.
'P. trichocarpa contains salicin, and has been used medicinally as an antipyretic
Antipyretic
Antipyretics ; an-tee-pahy-ret-iks; from the Greek anti, against, and pyreticus, are drugs or herbs that reduce fever. Normally, they will not lower body temperature if one does not have a fever. Antipyretics cause the hypothalamus to override an interleukin-induced increase in temperature...
, analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
and to control inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
.
Characteristics
- Size: 485 million base pairBase pairIn molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s. (Human genome: 3 billion base pairs) - Proportion of heterochromatinHeterochromatinHeterochromatin is a tightly packed form of DNA, which comes in different varieties. These varieties lie on a continuum between the two extremes of constitutive and facultative heterochromatin...
to euchromatinEuchromatinEuchromatin is a lightly packed form of chromatin that is rich in gene concentration, and is often under active transcription. Unlike heterochromatin, it is found in both cells with nuclei and cells without nuclei...
: 3:7 - Number of chromosomeChromosomeA chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s: 19 - Number of putative genes: 45,555, the largest number of genes ever recorded (estimate in September 2008)
- Mitochondrial genomeMitochondrionIn cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
: 803,000 base pairBase pairIn molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s, 52 geneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s - Chloroplast genomeChloroplastChloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
: 157,000 base pairBase pairIn molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
s, 101 geneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s
General information
The sequence of P. trichocarpa is that of an individual femaleFemale
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
specimen "Nisqually-1", named after the Nisqually River
Nisqually River
The Nisqually River is a river in west central Washington in the United States, approximately long. It drains part of the Cascade Range southwest of Tacoma, including the southern slope of Mount Rainier, and empties into the southern end of Puget Sound....
in the Washington state in the USA, where the specimen was collected. The sequencing
DNA sequencing
DNA sequencing includes several methods and technologies that are used for determining the order of the nucleotide bases—adenine, guanine, cytosine, and thymine—in a molecule of DNA....
was performed at the Joint Genome Institute
Joint Genome Institute
The U.S. Department of Energy Joint Genome Institute was created in 1997 to unite the expertise and resources in genome mapping, DNA sequencing, technology development, and information sciences pioneered at the DOE genome centers at Lawrence Berkeley National Laboratory , Lawrence Livermore...
by using the shotgun
Shotgun sequencing
In genetics, shotgun sequencing, also known as shotgun cloning, is a method used for sequencing long DNA strands. It is named by analogy with the rapidly-expanding, quasi-random firing pattern of a shotgun....
method. The depth of the sequencing was approximately 7.5 x (meaning that each base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
was sequenced
DNA sequencing
DNA sequencing includes several methods and technologies that are used for determining the order of the nucleotide bases—adenine, guanine, cytosine, and thymine—in a molecule of DNA....
on average 7.5 times). Genome annotation was done primarily by the Joint Genome Institute
Joint Genome Institute
The U.S. Department of Energy Joint Genome Institute was created in 1997 to unite the expertise and resources in genome mapping, DNA sequencing, technology development, and information sciences pioneered at the DOE genome centers at Lawrence Berkeley National Laboratory , Lawrence Livermore...
, the Oak Ridge National Laboratory
Oak Ridge National Laboratory
Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...
, the Umeå Plant Science Centre and Genome Canada.
Prior to the publication of P. trichocarpa genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
the only available plant genomes were those of thale cress
Arabidopsis thaliana
Arabidopsis thaliana is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, arabidopsis is popular as a model organism in plant biology and genetics...
and rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
, both of which are herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
. P. trichocarpa is the first woody plant genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
to be sequenced. Considering the economic importance of wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
and wood products, the availability of a tree genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
was necessary. The sequence also allows evolutionary comparisons and the elucidation of basic molecular differences between herbaceous
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
and woody plants.
Nomenclature
"Trichocarpa" is Greek for "hairy fruits". The following scientific names are now considered synonymous with Populus trichocarpa:
|
|
|