Polyploidy is a condition in which the cells of an organism have more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent. However, some organisms are polyploid, and polyploidy is especially common in plants. Most eukaryotes have diploid somatic cells, but produce haploid gametes by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally haploid. Males of bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis, the sporophyte generation is diploid and produces spores by meiosis.
Hordeum is a genus of annual and perennial plants in the grass family. They are native throughout the temperate regions of Africa, Eurasia, and the Americas.
Bromus tectorum, known as downy brome, drooping brome or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, southern Russia, Japan, South Africa, Australia, New Zealand, Iceland, Greenland, North America and western Central Asia. In the eastern US B. tectorum is common along roadsides and as a crop weed, but usually does not dominate an ecosystem. It has become a dominant species in the Intermountain West and parts of Canada, and displays especially invasive behavior in the sagebrush steppe ecosystems where it has been listed as noxious weed. B. tectorum often enters the site in an area that has been disturbed, and then quickly expands into the surrounding area through its rapid growth and prolific seed production.
Campanula rotundifolia, the harebell, Scottish bluebell, or bluebell of Scotland, is a species of flowering plant in the bellflower family Campanulaceae. This herbaceous perennial occurs in Europe from the north Mediterranean to the arctic. In Scotland, it is often known simply as bluebell. It produces its violet-blue, bell-shaped flowers in late summer and autumn.
A foxtail is a spikelet or cluster of a grass, that serves to disperse its seeds as a unit. Thus, the foxtail is a type of diaspore or plant dispersal unit. Some grasses that produce a foxtail are themselves called "foxtail", also "spear grass". They can become a health hazard for dogs and other domestic animals, and a nuisance for people.
During 10,000 years of cultivation, numerous forms of wheat, many of them hybrids, have developed under a combination of artificial and natural selection. This diversity has led to much confusion in the naming of wheats. This article explains how genetic and morphological characteristics of wheat influence its classification, and gives the most common botanical names of wheat in current use. Information on the cultivation and uses of wheat is at the main wheat page.
Triticeae is a botanical tribe within the subfamily Pooideae of grasses that includes genera with many domesticated species. Major crop genera found in this tribe include wheat, barley, and rye; crops in other genera include some for human consumption, and others used for animal feed or rangeland protection. Among the world's cultivated species, this tribe has some of the most complex genetic histories. An example is bread wheat, which contains the genomes of three species with only one being a wheat Triticum species. Seed storage proteins in the Triticeae are implicated in various food allergies and intolerances.
Hordeum jubatum, with common names foxtail barley, bobtail barley, squirreltail barley, and intermediate barley, is a perennial plant species in the grass family Poaceae. It occurs wild mainly in northern North America and adjacent northeastern Siberia. However, as it escaped often from gardens it can be found worldwide in areas with temperate to warm climates, and is considered a weed in many countries. The species is a polyploid and originated via hybridization of an East Asian Hordeum species with a close but extinct relative of Californian H. brachyantherum. It is grown as an ornamental plant for its attractive inflorescences and when done flowering for its infructescence.
Agropyron cristatum, the crested wheat grass, crested wheatgrass, fairway crested wheat grass, is a species in the family Poaceae. This plant is often used as forage and erosion control. It is well known as a widespread introduced species on the prairies of the United States and Canada.
Agropyron desertorum is a plant species in the family Poaceae which was originally from Russian and Siberian steppes until it was introduced to the United States from there between 1907 and 1913. Prior to its introduction it was believed that Desert wheatgrass and crested wheatgrass are different species. Currently it can still be found in Central and Western United States, except for Idaho, Kansas, Louisiana, Minnesota, Oklahoma, and Washington.
Puccinia coronata is a plant pathogen and causal agent of oat and barley crown rust. The pathogen occurs worldwide, infecting both wild and cultivated oats. Crown rust poses a threat to barley production, because the first infections in barley occur early in the season from local inoculum. Crown rusts have evolved many different physiological races within different species in response to host resistance. Each pathogenic race can attack a specific line of plants within the species typical host. For example, there are over 290 races of P. coronata. Crops with resistant phenotypes are often released, but within a few years virulent races have arisen and P. coronata can infect them.
Hordeum murinum, commonly known as wall barley or false barley, is a species of grass.
Hordeum pusillum, the little barley, is an annual grass native to the United States. It arrived via multiple long-distance dispersals of a southern South American species of Hordeum about one million years ago. Its closest relatives are therefore not the other North American taxa like meadow barley or foxtail barley, but rather Hordeum species of the pampas of central Argentina and Uruguay. It is less closely related to the Old World domesticated barley, from which it diverged about 12 million years ago. It is diploid.
A doubled haploid (DH) is a genotype formed when haploid cells undergo chromosome doubling. Artificial production of doubled haploids is important in plant breeding.
Elymus canadensis, commonly known as Canada wild rye or Canadian wildrye, is a species of wild rye native to much of North America. It is most abundant in the central plains and Great Plains. It grows in a number of ecosystems, including woodlands, savannas, dunes, and prairies, sometimes in areas that have been disturbed.
Panicum decompositum, known by the common names native millet, native panic, Australian millet, papa grass, and umbrella grass, is a species of perennial grass native to the inland of Australia. It occurs in every mainland state. The seeds can be cultivated to produce flour typically used in Aboriginal bushfood. The species is also considered to have relatively high palatability by livestock, making it suitable for grazing pastures.
Hordeum intercedens is an diploid, annual species of wild barley known by the common names bobtail barley and vernal barley. It is native to southern California and northern Baja California, where it is an increasingly rare member of the flora in saline and alkaline soils near seasonal waterflows and vernal pool habitats. Today most occurrences are located on the Channel Islands of California; many of the occurrences known from the mainland have been extirpated in the process of land development. This is an annual grass growing erect to bent in small tufts with stems up to 40 centimeters long. The inflorescence is a green spike up to 6.5 centimeters long made up of awned spikelets between 1 and 2 centimeters long.
Psathyrostachys juncea is a species of grass known by the common name Russian wildrye. It was formerly classified as Elymus junceus. It is native to Russia and China, and has been introduced to other parts of the world, such as Canada and the United States. Psathyrostachys juncea is a great source of food for grazing animals, as it has high nutrition value in its dense basal leaves, even in the late summer and autumn seasons. This species can grow and prosper in many harsh environments, making it an ideal candidate for improvement as it can grow in areas were farming is difficult. This species is a drought-resistant forage plant and can survive during the cool seasons. It is also a cross-pollinator and is self-sterile. This means that P. juncea cannot self-fertilize; it must find another plant of the same species with which to exchange gametes. Self-sterilization increases the genetic diversity of a species.
Dichanthium annulatum is a species of grass. It is commonly used as a forage for livestock.
Diploidization is the process of converting a polyploid genome back into a diploid one. Polyploidy is a product of whole genome duplication (WGD) and is followed by diploidization as a result of genome shock. The plant kingdom has undergone multiple events of polyploidization followed by diploidization in both ancient and recent lineages. It has also been hypothesized that vertebrate genomes have gone through two rounds of paleopolyploidy. The mechanisms of diploidization are poorly understood but patterns of chromosomal loss and evolution of novel genes are observed in the process.
