Hyaloperonospora arabidopsidis is a species from the family Peronosporaceae. It is an obligate parasite and the causal agent of the downy mildew of the plant model organism Arabidopsis thaliana. While H. arabidopsidis has for a long time been subsumed under Peronospora parasitica, recent studies have shown that H. parasitica is restricted to Capsella bursa-pastoris as a host plant. Like the other Hyaloperonospora species, H. arabidopsidis is specialized, it is so far known with certainty only from Arabidopsis thaliana as a host plant. Hyaloperonospora arabidopsidis encodes 10 different noncytotoxic NLPs. We discovered that these noncytotoxic NLPs, act as potent activators of the plant immune system in Arabidopsis thaliana. Ectopic expression of HaNLP3 in Arabidopsis triggered resistance to H. arabidopsidis, activated the expression of a large set of defense-related genes, caused a reduction of plant growth, associated with enhanced immunity. N- and C-terminal deletions of HaNLP3, as well as amino acid substitutions, pinpointed to a small central region of the protein, required to trigger immunity, indicating the protein acts as a microbe-associated molecular pattern.
Pel, Michiel J. C.. "Functional Analysis of Hyaloperonospora arabidopsidis RXLR Effectors". PLoS ONE. 9: e110624. Doi:10.1371/journal.pone.0110624. PMC 4222755. PMID 25375163. Marco, Francisco. "Overexpression of SAMDC1 gene in Arabidopsis thaliana increases expression of defense-related genes as well as resistance to Pseudomonas syringae and Hyaloperonospora arabidopsidis". Frontiers in Plant Science. FRONTIERS RESEARCH FOUNDATION
Brassica is a genus of plants in the mustard family. The members of the genus are informally known as cruciferous vegetables, cabbages, or mustard plants. Crops from this genus are sometimes called cole crops—derived from the Latin caulis, denoting the stem or stalk of a plant; the genus Brassica is known for its important agricultural and horticultural crops and includes a number of weeds, both of wild taxa and escapees from cultivation. Brassica species and varieties used for food include broccoli, cabbage, choy sum, rutabaga and some seeds used in the production of canola oil and the condiment mustard. Over 30 wild species and hybrids are in cultivation, plus numerous cultivars and hybrids of cultivated origin. Most are seasonal plants. Brassica plants have been the subject of much scientific interest for their agricultural importance. Six particular species evolved by the combining of chromosomes from three earlier species, as described by the Triangle of U theory; the genus is native to the Mediterranean and temperate regions of Asia.
Many wild species grow as weeds in North America, South America, Australia. A dislike for cabbage or broccoli can result from the fact that these plants contain a compound similar to phenylthiocarbamide, either bitter or tasteless to people depending on their taste buds. All parts of some species or other have been developed for food, including the root, leaves, flowers and seeds; some forms with white or purple foliage or flowerheads are sometimes grown for ornament. Brassica species are sometimes used as food plants by the larvae of a number of Lepidoptera species—see List of Lepidoptera that feed on Brassica. Brassica vegetables are regarded for their nutritional value, they provide high amounts of vitamin C and soluble fiber and contain nutrients with anticancer properties: 3,3'-diindolylmethane and selenium. Boiling reduces the level of anticancer compounds, but steaming and stir frying do not result in significant loss. Steaming these vegetable for three to four minutes is recommended to maximize sulforaphane.
Brassica vegetables are rich in indole-3-carbinol, a chemical which boosts DNA repair in cells in vitro and appears to block the growth of cancer cells in vitro. They are a good source of carotenoids, with broccoli having high levels. Researchers at the University of California at Berkeley have discovered that 3,3'-diindolylmethane in Brassica vegetables is a potent modulator of the innate immune response system with potent antiviral and anticancer activity. However, it is an antiandrogen but is known to be antiandrogenic only in hormone-sensitive prostate cancer cells; these vegetables contain goitrogens, some of which suppress thyroid function. Goitrogens can induce goiter in the absence of normal iodine intake. There is some disagreement among botanists on the classification and status of Brassica species and subspecies; the following is an abbreviated list, with an emphasis on economically important species. B. balearica: Mallorca cabbage B. carinata: Abyssinian mustard or Abyssinian cabbage, used to produce biodiesel B. elongata: elongated mustard B. fruticulosa: Mediterranean cabbage B. hilarionis: St Hilarion cabbage B. juncea: Indian mustard and leaf mustards, Sarepta mustard B. napus: rapeseed, rutabaga, Siberian kale B. narinosa: broadbeaked mustard B. nigra: black mustard B. oleracea: kale, collard greens, cauliflower, kai-lan, Brussels sprouts, kohlrabi B. perviridis: tender green, mustard spinach B. rapa: Chinese cabbage, rapini, komatsuna B. rupestris: brown mustard B. tournefortii: Asian mustard B. alba or B. hirta —see Sinapis alba B. geniculata —see Hirschfeldia incana B. kaber —see Sinapis arvensis Bayer CropScience announced it had sequenced the entire genome of rapeseed and its constituent genomes present in B. rapa and B. oleracea in 2009.
The B. rapa genome was sequenced by the Multinational Brassica Genome Project in 2011. This represents the A genome component of the amphidiploid crop species B. napus and B. juncea. ‘Brassica’ is Pliny's name for several cabbage-like plants. Media related to Brassica at Wikimedia Commons Data related to Brassica at Wikispecies
Brassicaceae or Cruciferae is a medium-sized and economically important family of flowering plants known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, some shrubs, with simple, although sometimes incised, alternatingly set leaves without stipules or in leaf rosettes, with terminal inflorescences without bracts, containing flowers with four free sepals, four free alternating petals, two short and four longer free stamens, a fruit with seeds in rows, divided by a thin wall; the family contains 4060 accepted species. The largest genera are Draba, Lepidium and Alyssum; the family contains the cruciferous vegetables, including species such as Brassica oleracea, Brassica rapa, Brassica napus, Raphanus sativus, Armoracia rusticana, but a cut-flower Matthiola and the model organism Arabidopsis thaliana. Pieris rapae and other butterflies of the family Pieridae are some of the best-known pests of Brassicaceae species planted as commercial crops. Trichoplusia ni moth is becoming problematic for crucifers due to its resistance to used pest control methods.
Some rarer Pieris butterflies, such as Pieris virginiensis, depend upon native mustards for their survival, in their native habitats. Some non-native mustards, such as garlic mustard, Alliaria petiolata, an invasive species in the United States, can be toxic to their larvae. Carl Linnaeus in 1753 regarded the Brassicaceae as a natural group, naming them "Klass" Tetradynamia. Alfred Barton Rendle placed the family in the order Rhoedales, while George Bentham and Joseph Dalton Hooker in their system published from 1862–1883, assigned it to their cohort Parietales. Following Bentham and Hooker, John Hutchinson in 1948 and again in 1964 thought the Brassicaceae to stem from near the Papaveraceae. In 1994, a group of scientists including Walter Stephen Judd suggested to include the Capparaceae in the Brassicaceae. Early DNA-analysis showed that the Capparaceae—as defined at that moment—were paraphyletic, it was suggested to assign the genera closest to the Brassicaceae to the Cleomaceae; the Cleomaceae and Brassicaceae diverged 41 million years ago.
All three families have been placed in one order. The APG II system, merged Cleomaceae and Brassicaceae. Other classifications have continued to recognize the Capparaceae, but with a more restricted circumscription, either including Cleome and its relatives in the Brassicaceae or recognizing them in the segregate family Cleomaceae; the APG III system has adopted this last solution, but this may change as a consensus arises on this point. Current insights in the relationships of the Brassicaceae, based on a 2012 DNA-analysis, are summarized in the following tree. Early classifications depended on morphological comparison only, but because of extensive convergent evolution, these do not provide a reliable phylogeny. Although a substantial effort was made through molecular phylogenetic studies, the relationships within the Brassicaceae have not always been well resolved yet, it has long been clear. One analysis from 2014 represented the relation between 39 tribes with the following tree; the name Brassicaceae comes to international scientific vocabulary from New Latin, from Brassica, the type genus, + -aceae, a standardized suffix for plant family names in modern taxonomy.
The genus name comes from the Classical Latin word brassica, referring to cabbage and other cruciferous vegetables. The alternative older name, meaning "cross-bearing", describes the four petals of mustard flowers, which resemble a cross. Cruciferae is one of eight plant family names, not derived from a genus name and without the suffix -aceae that are authorized alternative names. Version 1 of the Plantlist website lists 349 genera. Species belonging to the Brassicaceae are annual, biennial, or perennial herbaceous plants, some are dwarf shrubs or shrubs, few vines. Although terrestrial, a few species such as water awlwort live submerged in fresh water, they may have a taproot or a sometimes woody caudex that may have few or many branches, some have thin or tuberous rhizomes, or develop runners. Few species have multi-cellular glands. Hairs consist of one cell and occur in many forms: from simple to forked, star-, tree- or T-shaped taking the form of a shield or scale, they are never topped by a gland.
The stems may be upright, rise up towards the tip, or lie flat, are herbaceous but sometimes woody. Stems carry leaves or the stems may be leafless, some species lack stems altogether; the leaves do not have stipules, but there may be a pair of glands at base of leafstalks and flowerstalks. The leaf may have a leafstalk; the leaf blade is simple, entire or dissected trifoliolate or pinnately compound. A leaf rosette at the base may be absent; the leaves along the stem are always alternately arranged apparently opposite. The stomata are of the anisocytic type; the genome size of Brassicaceae compared to that of other Angiosperm families is small to small, varying from 150 Mbp in Arabidopsis thaliana and Sphaerocardamum spp. to 2375 Mbp Bunias orientalis. The number of homologous chromosome sets varies from four in some Physaria and Stenopetalum species, five in other Physaria and Stenopeta
Hyaloperonospora is a genus of downy mildews, several of which cause downy mildew disease on various members of the order Brassicales including broccoli and cabbage. Species include Hyaloperonospora arabidopsidis Göker, Riethm. Weiss & Oberw. 2003 Hyaloperonospora brassicae Göker, Riethm. Weiss & Oberw. 2003 Hyaloperonospora parasitica Constant. 2002
Peronosporaceae are a family of water moulds that contains 21 genera, comprising more than 600 species. Most of them are called downy mildews. Peronosporaceae are obligate biotrophic plant pathogens, they parasitize their host plants as an intercellular mycelium using haustoria to penetrate the host cells. The downy mildews reproduce asexually by forming sporangia on distinctive white sporangiophores formed on the lower surface of infected leaves; these constitute the "downy mildew". The sporangia are wind-dispersed to the surface of other leaves. According to the genus concerned, the sporangia may germinate by forming zoospores, thus resembling Phytophthora, or by germ-tube. In the latter case, the sporangia behave as conidia and are referred to as such. Sexual reproduction is via oospores; the parasitized plants are angiosperms, most Peronosporaceae are pathogens of herbaceous dicots. Some downy mildew genera have a more restricted host range, e.g. Basidiophora, Paraperonospora and Bremia on Asteraceae.
The largest genera and Plasmopara, have a wide host range. Peronosporaceae of economic importance include those; the latter species has such a delicate spore that it times its spore release for sunrise, a time of high ambient moisture and dew accumulation, so that its spores are less to succumb to desiccation and light. Bremia lactucae is a parasite on Plasmopara halstedii on sunflower. C. J. Alexopolous, Charles W. Mims, M. Blackwell et al. Introductory Mycology, 4th ed. ISBN 978-0-471-52229-4 Göker, M.. "How do obligate parasites evolve? A multi-gene phylogenetic analysis of downy mildews". Fungal Genetics and Biology. 44: 105–122. Doi:10.1016/j.fgb.2006.07.005. PMID 16990040. Thines, M. Voglmayr, H. & Göker, M. Taxonomy and phylogeny of the downy mildews. In: Lamour, K. & Kamoun, S. Oomycete genetics and Genomics, pp. 47–55. ISBN 978-0-470-25567-4
Arabidopsis thaliana, the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. A. thaliana is considered a weed. A winter annual with a short life cycle, A. thaliana is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, A. thaliana has a small genome of 135 megabase pairs. It was the first plant to have its genome sequenced, is a popular tool for understanding the molecular biology of many plant traits, including flower development and light sensing. Arabidopsis thaliana is an annual plant growing to 20–25 cm tall; the leaves form a rosette at the base of the plant, with a few leaves on the flowering stem. The basal leaves are green to purplish in color, 1.5–5 cm long and 2–10 mm broad, with an entire to coarsely serrated margin. Leaves are covered with unicellular hairs; the flowers are 3 mm in diameter, arranged in a corymb. The fruit is a siliqua 5 -- 20 mm long. Roots are simple in structure, with a single primary root that grows vertically downward producing smaller lateral roots.
These roots form interactions with rhizosphere bacteria such as Bacillus megaterium. A. thaliana can complete its entire lifecycle in six weeks. The central stem that produces flowers grows after about three weeks, the flowers self-pollinate. In the lab, A. thaliana may be grown in Petri plates, pots, or hydroponics, under fluorescent lights or in a greenhouse. The plant was first described in 1577 in the Harz Mountains by Johannes Thal, a physician from Nordhausen, Thüringen, who called it Pilosella siliquosa. In 1753, Carl Linnaeus renamed the plant Arabis thaliana in honor of Thal. In 1842, the German botanist Gustav Heynhold erected the new genus Arabidopsis and placed the plant in that genus; the genus name, comes from Greek, meaning "resembling Arabis". Thousands of natural inbred accessions of A. thaliana have been collected from throughout its natural and introduced range. These accessions exhibit considerable genetic and phenotypic variation which can be used to study the adaptation of this species to different environments.
A. thaliana is native to Europe, Asia and human observations indicate its geographic distribution is rather continuous from the Mediterranean to Scandinavia and Spain to Greece. It appears to be native in tropical alpine ecosystems in Africa and South Africa, it has been introduced and naturalized worldwide, including in North America ca. the 17th century. A. Thaliana grows and pioneers rocky and calcareous soils, it is considered a weed, due to its widespread distribution in agricultural fields, railway lines, waste ground and other disturbed habitat, but due to its limited competitive ability and small size it is not categorized as a noxious weed. Like most Brassicaceae species, A. thaliana is edible by humans as a salad or cooked, but it does not enjoy a widespread use as a spring vegetable. Botanists and biologists began to research A. thaliana in the early 1900s, the first systematic description of mutants was done around 1945. A. thaliana is now used for studying plant sciences, including genetics, population genetics, plant development.
Although A. thaliana has little direct significance for agriculture, it has several traits that make it a useful model for understanding the genetic and molecular biology of flowering plants. The first mutant in A. thaliana was documented in 1873 by Alexander Braun, describing a double flower phenotype. However, not until 1943 did Friedrich Laibach propose A. thaliana as a model organism. His student, Erna Reinholz, published her thesis on A. thaliana in 1945, describing the first collection of A. thaliana mutants that they generated using X-ray mutagenesis. Laibach continued his important contributions to A. thaliana research by collecting a large number of accessions. With the help of Albert Kranz, these were organised into a large collection of 750 natural accessions of A. thaliana from around the world. In the 1950s and 1960s, John Langridge and George Rédei played an important role in establishing A. thaliana as a useful organism for biological laboratory experiments. Rédei wrote several scholarly reviews instrumental in introducing the model to the scientific community.
The start of the A. thaliana research community dates to a newsletter called Arabidopsis Information Service, established in 1964. The first International Arabidopsis Conference was held in Göttingen, Germany. In the 1980s, A. thaliana started to become used in plant research laboratories around the world. It was one of several candidates that included maize and tobacco; the latter two were attractive, since they were transformable with the then-current technologies, while maize was a well-established genetic model for plant biology. 1986 was a breakthrough year for A. thaliana as a model plant, in which T-DNA-mediated transformation and the first cloned A. thaliana gene were described. The small size of its genome, the fact that it is diploid, makes Arabidopsis thaliana useful for genetic mapping and sequencing — with about 135 mega base pairs and five chromosomes, A. thaliana has one of the smallest genomes among plants. It was long thought to have the small
A conidium, sometimes termed an asexual chlamydospore or chlamydoconidium, is an asexual, non-motile spore of a fungus. The name comes from the Greek word for κόνις kónis, they are called mitospores due to the way they are generated through the cellular process of mitosis. The two new haploid cells are genetically identical to the haploid parent, can develop into new organisms if conditions are favorable, serve in biological dispersal. Asexual reproduction in ascomycetes is by the formation of conidia, which are borne on specialized stalks called conidiophores; the morphology of these specialized conidiophores is distinctive between species and, before the development of molecular techniques at the end of the 20th century, was used for identification of species. The terms microconidia and macroconidia are sometimes used. There are two main types of conidium development: Blastic conidiogenesis, where the spore is evident before it separates from the conidiogenic hypha, giving rise to it, Thallic conidiogenesis, where first a cross-wall appears and thus the created cell develops into a spore.
A conidium conidial anastomosis tubes in specific conditions. These two are some of the specialized hyphae; the germ tubes will grow to form the fungal mycelia. The conidial anastomosis tubes are physiologically distinct from germ tubes. After conidia are induced to form conidial anastomosis tubes, they grow homing toward each other, they fuse. Once fusion happens, the nuclei can pass through fused CATs; these are events of not sexual reproduction. Fusion between these cells seems to be important for some fungi during early stages of colony establishment; the production of these cells has been suggested to occur in 73 different species of fungi. Conidiogenesis is an important mechanism of spread of plant pathogens. In some cases, specialized macroscopic fruiting structures 1mm or so in diameter containing masses of conidia are formed under the skin of the host plant and erupt through the surface and allow the spores to be distributed by wind and rain. One of these structures is called a conidioma.
Two important types of conidiomata, distinguished by their form, are: pycnidia, which are flask-shaped, acervuli, which have a simpler cushion-like form. Pycnidial conidiomata or pycnidia form in the fungal tissue itself, are shaped like a bulging vase; the conidia are released through a small opening at the ostiole. Acervular conidiomata, or acervuli, are cushion-like structures that form within the tissues of a host organism: subcuticular, lying under the outer layer of the plant, inside the outer cell layer, under the epidermis, or deeper inside the host, they develop a flat layer of short conidiophores which produce masses of spores. The increasing pressure leads to the splitting of the epidermis and cuticle and allows release of the conidia from the tissue. Conidia are always present in the air. An average person inhales 40 conidia per hour. Conidia are the method by which some harmless but heat-tolerating, common fungi establish infection in certain types of immunocompromised patients, their immune system is not strong enough to fight off the fungus, it may, for example, colonise the lung, resulting in a pulmonary infection.
Arthroconidium Asexual reproduction Ascocarp Basidiocarp Budding Chlamydospore Gemma Phialide "Conidia". The New Student's Reference Work. 1914