49-469: Acacia heterophylla var. latifolia Benth. Acacia kauaiensis Hillebr. Racosperma koa (A.Gray) Pedley Acacia koa , commonly known as koa , is a species of flowering tree in the family Fabaceae . It is endemic to the Hawaiian Islands , where it is the second most common tree. The highest populations are on Hawaiʻi , Maui and Oʻahu . The name koa in
98-460: A cyanobiont (cyanobacteria such as Nostoc ) which fix nitrogen for them: Some symbiotic relationships involving agriculturally-important plants are: A method for nitrogen fixation was first described by Henry Cavendish in 1784 using electric arcs reacting nitrogen and oxygen in air. This method was implemented in the Birkeland–Eyde process of 1903. The fixation of nitrogen by lightning
147-399: A nitrogenase enzyme. The overall reaction for BNF is: N 2 + 16ATP + 16H 2 O + 8e + 8H → 2NH 3 +H 2 + 16ADP + 16P i The process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent of H 2 . The conversion of N 2 into ammonia occurs at a metal cluster called FeMoco , an abbreviation for
196-543: A critical threshold. The specialized heterocyst cell is necessary for the performance of nitrogenase as a result of its sensitivity to ambient oxygen. Nitrogenase consist of two proteins, a catalytic iron-dependent protein, commonly referred to as MoFe protein and a reducing iron-only protein (Fe protein). There are three different iron dependent proteins, molybdenum -dependent, vanadium -dependent, and iron -only, with all three nitrogenase protein variations containing an iron protein component. Molybdenum-dependent nitrogenase
245-472: A distance of 18,000 km) is thought to have been seed-carrying by birds such as petrels (the seeds of these species are not adapted for prolonged immersion in seawater). Both species also have very similar ecological niches , which differ from that of A. melanoxylon . [REDACTED] Media related to Acacia heterophylla at Wikimedia Commons This article on a tree of the Fabaceae family
294-436: A good site. Initially, bipinnately compound leaves with 12–24 pairs of leaflets grow on the koa plant, much like other members of the pea family . At about 6–9 months of age, however, thick sickle-shaped "leaves" that are not compound begin to grow. These are phyllodes , blades that develop as an expansion of the leaf petiole . The vertically flattened orientation of the phyllodes allows sunlight to pass to lower levels of
343-493: A hard seed coat , and this allows them to remain dormant for up to 25 years. Scarification is needed before A. koa seeds will germinate . Koa is endemic to the islands of Hawaiʻi , Molokaʻi , Maui , Lānaʻi , Oʻahu , and Kauaʻi , where it grows at elevations of 100–2,300 m (330–7,550 ft). It requires 850–5,000 mm (33–197 in) of annual rainfall. Acidic to neutral soils ( pH of 4–7.4) that are either an Inceptisol derived from volcanic ash or
392-739: A koa- veneered topwood on certain models. Fender made limited edition koa wood models of the Telecaster and the Stratocaster in 2006. Trey Anastasio , guitarist for the band Phish , primarily uses a koa hollowbody Languedoc guitar. Commercial silviculture of koa takes 20 to 25 years before a tree is of useful size. Taylor, Collings and Martin are few among the many other brands that use that tonewood for manufacturing acoustic guitars. Among other Pacific Islands of volcanic (non- continental ) origin, only Vanuatu has native Acacia species. A. heterophylla , from distant Réunion ,
441-411: A length of 7.5–15 cm (3.0–5.9 in) and a width of 1.5–2.5 cm (0.59–0.98 in). Each pod contains an average of 12 seeds . The 6–12 mm (0.24–0.47 in) long, 4–7 mm (0.16–0.28 in) wide seeds are flattened ellipsoids and range from dark brown to black in color. The pods are mature and ready for propagation after turning from green to brown or black. Seeds are covered with
490-447: A low nitrogen content, has been shown to host a diazotrophic community. The bacteria enrich the wood substrate with nitrogen through fixation, thus enabling deadwood decomposition by fungi. Nitrogenases are rapidly degraded by oxygen. For this reason, many bacteria cease production of the enzyme in the presence of oxygen. Many nitrogen-fixing organisms exist only in anaerobic conditions, respiring to draw down oxygen levels, or binding
539-424: A new era of soil science ." In 1901, Beijerinck showed that Azotobacter chroococcum was able to fix atmospheric nitrogen. This was the first species of the azotobacter genus, so-named by him. It is also the first known diazotroph , species that use diatomic nitrogen as a step in the complete nitrogen cycle . Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by
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#1732772541403588-499: A well-drained histosol are preferred. Its ability to fix nitrogen allows it to grow in very young volcanic soils. Koa and ʻōhiʻa lehua ( Metrosideros polymorpha ) dominate the canopy of Hawaiian mixed mesic forests . It is also common in wet forests . The koa's trunk was used by ancient Hawaiians to build waʻa ( dugout outrigger canoes ) and papa heʻe nalu ( surfboards ). Only paipo ( bodyboards ), kikoʻo , and alaia surfboards were made from koa, however; olo ,
637-467: Is Acacia koa of Hawaii; the estimated time of divergence is about 1.4 million years ago. A. heterophylla sequences nest within those of the more diverse A. koa , making the latter species paraphyletic . Both species are descended from an ancestral species in Australia, presumably their sister species , Acacia melanoxylon ; the means of dispersal to Hawaii and then to Réunion (the latter trip
686-431: Is a stub . You can help Misplaced Pages by expanding it . Nitrogen fixation Nitrogen fixation is a chemical process by which molecular dinitrogen ( N 2 ) is converted into ammonia ( NH 3 ). It occurs both biologically and abiologically in chemical industries . Biological nitrogen fixation or diazotrophy is catalyzed by enzymes called nitrogenases . These enzyme complexes are encoded by
735-401: Is a large tree , typically attaining a height of 15–25 m (49–82 ft) and a spread of 6–12 m (20–39 ft). In deep volcanic ash , a koa tree can reach a height of 30 m (98 ft), a circumference of 6 m (20 ft), and a spread of 38 m (125 ft). It is one of the fastest-growing Hawaiian trees, capable of reaching 6–9 m (20–30 ft) in five years on
784-408: Is a required precursor to fertilizers , explosives , and other products. The Haber process requires high pressures (around 200 atm) and high temperatures (at least 400 °C), which are routine conditions for industrial catalysis. This process uses natural gas as a hydrogen source and air as a nitrogen source. The ammonia product has resulted in an intensification of nitrogen fertilizer globally and
833-532: Is a very similar natural occurring process. The possibility that atmospheric nitrogen reacts with certain chemicals was first observed by Desfosses in 1828. He observed that mixtures of alkali metal oxides and carbon react with nitrogen at high temperatures. With the use of barium carbonate as starting material, the first commercial process became available in the 1860s, developed by Margueritte and Sourdeval. The resulting barium cyanide reacts with steam, yielding ammonia. In 1898 Frank and Caro developed what
882-566: Is credited with supporting the expansion of the human population from around 2 billion in the early 20th century to roughly 8 billion people now. Much research has been conducted on the discovery of catalysts for nitrogen fixation, often with the goal of lowering energy requirements. However, such research has thus far failed to approach the efficiency and ease of the Haber process. Many compounds react with atmospheric nitrogen to give dinitrogen complexes . The first dinitrogen complex to be reported
931-442: Is dependent on many factors, including the legume and air and soil conditions. For example, nitrogen fixation by red clover can range from 50 to 200 lb/acre (56 to 224 kg/ha). The ability to fix nitrogen in nodules is present in actinorhizal plants such as alder and bayberry , with the help of Frankia bacteria. They are found in 25 genera in the orders Cucurbitales , Fagales and Rosales , which together with
980-586: Is found in dry areas. It is most easily distinguished by having smaller seeds that are arranged end-to-end in the pod, rather than side by side. The phyllodes are also usually straighter, though this character is variable in both species. The wood is denser, harder, and more finely grained than koa wood. Koaiʻa has been much more heavily impacted by cattle and is now rare, but can be seen on ranch land in North Kohala . The koa population has suffered from grazing and logging . Many wet forest areas, where
1029-408: Is genetically regulated, and the activity of the protein complex is dependent on ambient oxygen concentrations, and intra- and extracellular concentrations of ammonia and oxidized nitrogen species (nitrate and nitrite). Additionally, the combined concentrations of both ammonium and nitrate are thought to inhibit N Fix , specifically when intracellular concentrations of 2- oxoglutarate (2-OG) exceed
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#17327725414031078-571: Is known as the Frank–Caro process to fix nitrogen in the form of calcium cyanamide . The process was eclipsed by the Haber process , which was discovered in 1909. The dominant industrial method for producing ammonia is the Haber process also known as the Haber-Bosch process. Fertilizer production is now the largest source of human-produced fixed nitrogen in the terrestrial ecosystem . Ammonia
1127-796: Is no conclusive agreement on which form of nitrogenase arose first. Diazotrophs are widespread within domain Bacteria including cyanobacteria (e.g. the highly significant Trichodesmium and Cyanothece ), green sulfur bacteria , purple sulfur bacteria , Azotobacteraceae , rhizobia and Frankia . Several obligately anaerobic bacteria fix nitrogen including many (but not all) Clostridium spp. Some archaea such as Methanosarcina acetivorans also fix nitrogen, and several other methanogenic taxa , are significant contributors to nitrogen fixation in oxygen-deficient soils. Cyanobacteria , commonly known as blue-green algae, inhabit nearly all illuminated environments on Earth and play key roles in
1176-553: Is often possible to begin reforestation in a pasture by disk harrowing the soil, as this scarifies seeds in the soil and encourages large numbers of koa to germinate. Experiments at the Hakalau Forest National Wildlife Refuge have shown that ʻōhiʻa lehua ( Metrosideros polymorpha ) survives best in pasture when planted under koa. This is because koa trees reduce radiative cooling , preventing frost damage to ʻōhiʻa lehua seedlings. Koa
1225-590: Is the most commonly present nitrogenase. The different types of nitrogenase can be determined by the specific iron protein component. Nitrogenase is highly conserved. Gene expression through DNA sequencing can distinguish which protein complex is present in the microorganism and potentially being expressed. Most frequently, the nif H gene is used to identify the presence of molybdenum-dependent nitrogenase, followed by closely related nitrogenase reductases (component II) vnf H and anf H representing vanadium-dependent and iron-only nitrogenase, respectively. In studying
1274-558: Is the preferred host plant for the caterpillars of the green Hawaiian blue ( Udara blackburni ), which eat the flowers and fruits. Adults drink nectar from the flowers. Koa sap is eaten by the adult Kamehameha butterfly ( Vanessa tameamea ). The koa bug ( Coleotichus blackburniae ) uses its rostrum to suck the contents out of koa seeds. Koa is vulnerable to infection by koa wilt . Acacia heterophylla Acacia brevipes A.Cunn. Acacia xiphoclada Baker Mimosa heterophylla Lam. Acacia heterophylla ,
1323-711: Is very similar and has been suggested to be the closest relative of koa. Genetic sequence analysis results announced in 2014 confirmed this close relationship; the estimated time of divergence is about 1.4 million years ago. A. heterophylla sequences nest within those of the more diverse A. koa , making the latter paraphyletic . Both species are thought to be descended from an ancestral species in Australia, presumably their sister species , Acacia melanoxylon . Dispersals most likely occurred via seed-carrying by birds such as petrels . Both species have very similar ecological niches , which differ from that of A. melanoxylon . A closely related species, koaiʻa or koaiʻe ( A. koaia ),
1372-569: The Nif genes (or Nif homologs ) and contain iron , often with a second metal (usually molybdenum , but sometimes vanadium ). Some nitrogen-fixing bacteria have symbiotic relationships with plants , especially legumes , mosses and aquatic ferns such as Azolla . Looser non-symbiotic relationships between diazotrophs and plants are often referred to as associative, as seen in nitrogen fixation on rice roots. Nitrogen fixation occurs between some termites and fungi . It occurs naturally in
1421-485: The Fabales form a nitrogen-fixing clade of eurosids . The ability to fix nitrogen is not universally present in these families. For example, of 122 Rosaceae genera, only four fix nitrogen. Fabales were the first lineage to branch off this nitrogen-fixing clade; thus, the ability to fix nitrogen may be plesiomorphic and subsequently lost in most descendants of the original nitrogen-fixing plant; however, it may be that
1470-715: The Hawaiian language ultimately comes from Proto-Austronesian * teRas meaning "core" or " ironwood "; many names referring to certain ironwood or heartwood species in Southeast Asia and Oceania such as Vitex parviflora ( tugás in Cebuano ), Eusideroxylon zwageri ( togas in Tombonuwo ), and Intsia bijuga ( dort in Palauan ) descend from this root. Koa also means brave, bold, fearless, or warrior. Koa
1519-522: The highland tamarind , is a tree (or shrub in its higher places) endemic to Réunion island where it is commonly named tamarin des hauts The tree has a juvenile stage where its leaves have a pinnate arrangement, but in the adult stage the leaves diminish and the phyllode becomes the dominant photosynthetic structure. It has been introduced into Madagascar where it grows in a subhumid climate at an altitude of about 500–1000 m above sea level. Genetic sequence analysis has shown its closest relative
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1568-414: The air by means of NO x production by lightning . Nitrogen fixation is essential to life on Earth because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds such as amino acids , polypeptides and proteins , nucleoside triphosphates and nucleic acids . As part of the nitrogen cycle , it is essential for soil fertility and
1617-697: The amount of nitrogen fixed in the ocean is at least as much as that on land. The colonial marine cyanobacterium Trichodesmium is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally. Marine surface lichens and non-photosynthetic bacteria belonging in Proteobacteria and Planctomycetes fixate significant atmospheric nitrogen. Species of nitrogen fixing cyanobacteria in fresh waters include: Aphanizomenon and Dolichospermum (previously Anabaena). Such species have specialized cells called heterocytes , in which nitrogen fixation occurs via
1666-409: The basic genetic and physiological requirements were present in an incipient state in the most recent common ancestors of all these plants, but only evolved to full function in some of them. In addition, Trema ( Parasponia ), a tropical genus in the family Cannabaceae , is unusually able to interact with rhizobia and form nitrogen-fixing nodules. Some other plants live in association with
1715-561: The carbon and nitrogen cycle of the biosphere . In general, cyanobacteria can use various inorganic and organic sources of combined nitrogen, such as nitrate , nitrite , ammonium , urea , or some amino acids . Several cyanobacteria strains are also capable of diazotrophic growth, an ability that may have been present in their last common ancestor in the Archean eon. Nitrogen fixation not only naturally occurs in soils but also aquatic systems, including both freshwater and marine. Indeed,
1764-498: The ecology and evolution of nitrogen-fixing bacteria , the nifH gene is the biomarker most widely used. nif H has two similar genes anf H and vnfH that also encode for the nitrogenase reductase component of the nitrogenase complex. Nitrogenase is thought to have evolved sometime between 1.5-2.2 billion years ago (Ga), although some isotopic support showing nitrogenase evolution as early as around 3.2 Ga. Nitrogenase appears to have evolved from maturase -like proteins, although
1813-410: The function of the preceding protein is currently unknown. Nitrogenase has three different forms ( Nif, Anf, and Vnf ) that correspond with the metal found in the active site of the protein (Molybdenum, Iron, and Vanadium respectively). Marine metal abundances over Earth’s geologic timeline are thought to have driven the relative abundance of which form of nitrogenase was most common. Currently, there
1862-406: The growth of terrestrial and semiaquatic vegetations , upon which all consumers of those ecosystems rely for biomass . Nitrogen fixation is thus crucial to the food security of human societies in sustaining agricultural yields (especially staple crops ), livestock feeds ( forage or fodder ) and fishery (both wild and farmed ) harvests . It is also indirectly relevant to
1911-548: The iron- molybdenum cofactor. The mechanism proceeds via a series of protonation and reduction steps wherein the FeMoco active site hydrogenates the N 2 substrate. In free-living diazotrophs , nitrogenase-generated ammonia is assimilated into glutamate through the glutamine synthetase /glutamate synthase pathway. The microbial nif genes required for nitrogen fixation are widely distributed in diverse environments. For example, decomposing wood, which generally has
1960-511: The largest koa grow, have been logged out, and it now comes largely from dead or dying trees or farms on private lands. Although formerly used for outrigger canoes , there are few koa remaining which are both large and straight enough to do so today. In areas where cattle are present, koa regeneration is almost completely suppressed. However, if the cattle are removed, koa are among the few native Hawaiian plants able to germinate in grassland, and can be instrumental in restoring native forest . It
2009-530: The longest surfboards, were made from the lighter and more buoyant wiliwili ( Erythrina sandwicensis ). The reddish wood is very similar in strength and weight to that of Black Walnut ( Juglans nigra ), with a specific gravity of 0.55, and is now sought for use in wood carving and furniture . Koa is also a tonewood , often used in the construction of ukuleles , acoustic guitars , and Weissenborn -style Hawaiian steel guitars . B.C. Rich used koa on some of their electric guitars as well, and still uses
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2058-492: The manufacture of all nitrogenous industrial products , which include fertilizers , pharmaceuticals , textiles , dyes and explosives . Biological nitrogen fixation was discovered by Jean-Baptiste Boussingault in 1838. Later, in 1880, the process by which it happens was discovered by German agronomist Hermann Hellriegel and Hermann Wilfarth [ de ] and was fully described by Dutch microbiologist Martinus Beijerinck . "The protracted investigations of
2107-473: The nitrogenase enzyme. One type of organelle can turn nitrogen gas into a biologically available form. This nitroplast was discovered in algae . Plants that contribute to nitrogen fixation include those of the legume family — Fabaceae — with taxa such as kudzu , clover , soybean , alfalfa , lupin , peanut and rooibos . They contain symbiotic rhizobia bacteria within nodules in their root systems , producing nitrogen compounds that help
2156-409: The oxygen with a protein such as leghemoglobin . Atmospheric nitrogen is inaccessible to most organisms, because its triple covalent bond is very strong. Most take up fixed nitrogen from various sources. For every 100 atoms of carbon, roughly 2 to 20 atoms of nitrogen are assimilated. The atomic ratio of carbon (C) : nitrogen (N) : phosphorus (P) observed on average in planktonic biomass
2205-475: The plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants; this helps to fertilize the soil . The great majority of legumes have this association, but a few genera (e.g., Styphnolobium ) do not. In many traditional farming practices, fields are rotated through various types of crops, which usually include one consisting mainly or entirely of clover . Fixation efficiency in soil
2254-462: The relation of plants to the acquisition of nitrogen begun by de Saussure , Ville , Lawes , Gilbert and others, and culminated in the discovery of symbiotic fixation by Hellriegel and Wilfarth in 1887." "Experiments by Bossingault in 1855 and Pugh, Gilbert & Lawes in 1887 had shown that nitrogen did not enter the plant directly. The discovery of the role of nitrogen fixing bacteria by Herman Hellriegel and Herman Wilfarth in 1886-1888 would open
2303-470: The tree. True leaves are entirely replaced by 7–25 cm (2.8–9.8 in) long, 0.5–2.5 cm (0.20–0.98 in) wide phyllodes on an adult tree. Flowers of the koa tree are pale-yellow spherical racemes with a diameter of 8–10 mm (0.31–0.39 in). Flowering may be seasonal or year round depending on the location. Fruit production start occurring when a koa tree is between 5 and 30 years old. The fruit are legumes , also called pods, with
2352-767: Was Ru(NH 3 ) 5 ( N 2 ) . Some soluble complexes do catalyze nitrogen fixation. Nitrogen can be fixed by lightning converting nitrogen gas ( N 2 ) and oxygen gas ( O 2 ) in the atmosphere into NO x ( nitrogen oxides ). The N 2 molecule is highly stable and nonreactive due to the triple bond between the nitrogen atoms. Lightning produces enough energy and heat to break this bond allowing nitrogen atoms to react with oxygen, forming NO x . These compounds cannot be used by plants, but as this molecule cools, it reacts with oxygen to form NO 2 , which in turn reacts with water to produce HNO 2 ( nitrous acid ) or HNO 3 ( nitric acid ). When these acids seep into
2401-422: Was originally described by Alfred Redfield, who determined the stoichiometric relationship between C:N:P atoms, The Redfield Ratio, to be 106:16:1. The protein complex nitrogenase is responsible for catalyzing the reduction of nitrogen gas (N 2 ) to ammonia (NH 3 ). In cyanobacteria , this enzyme system is housed in a specialized cell called the heterocyst . The production of the nitrogenase complex
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