Orobanche
Striga
Germination
Plant Roots
Helianthus
Vicia sativa
Lactones
Autotrophic Processes
Host-Parasite Interactions
Infection of tubercles of the parasitic weed Orobanche aegyptiaca by mycoherbicidal Fusarium species. (1/33)
Progression of the infection by host-specific strains of Fusarium oxysporum and Fusarium arthrosporioides of Orobanche aegyptiaca (Egyptian broomrape) tubercles attached to tomato roots was tracked using light, confocal and electron microscopy. Mycelia transformed with the gene for green fluorescent protein were viewed using a confocal microscope. Fungal penetration was preceded by a rapid loss of starch, with approx. 10 % remaining at 9 h and no measurable starch at 24 h. Penetration into the Orobanche tubercles began by 12 h after inoculation. Hyphae penetrated the outer six cell layers by 24 h, reaching the centre of the tubercles by 48 h and infecting nearly all cells by 72 h. Most of the infected tubercles were dead by 96 h. Breakdown of cell walls and the disintegration of cytoplasm in and around the infected cells occurred between 48 and 96 h. Lignin-like material increased in tubercle cells of infected tissues over time, but did not appear to be effective in limiting fungal penetration or spread. Callose, suberin, constitutive toxins and phytoalexins were not detected in infected tubercles, suggesting that there are no obvious defence mechanisms to overcome. Both Fusarium spp. pathogenic on Orobanche produced fumonisin-like ceramide synthase inhibitors, while fusaric acid was produced only by F. oxysporum in liquid culture. The organisms do not have sufficient virulence for field use (based on glasshouse testing), suggesting that virulence should be transgenically enhanced or additional isolates sought. (+info)Resistance to broomrape (Orobanche spp.) in sunflower (Helianthus annuus L.) is temperature dependent. (2/33)
The effects of various temperature regimes in the range 29-17/21-9 degrees C day/night on each stage of the parasitism process of Orobanche cumana and O. aegyptiaca on sunflower were studied under controlled conditions in polyethylene bags. The response of the resistant sunflower variety 'Ambar' was expressed as the degeneration of the parasite tissues after its establishment in the plant roots, and this stage was found to be temperature dependent. The degeneration rate of Orobanche tubercles in the resistant sunflower variety was also found to be temperature dependent and was about five times as great as that in the sensitive variety in the highest temperature regime tested of 29/21 degrees C day/night. The ability to reject the parasite by causing its degeneration and death is the main factor that determines the resistance. As the temperature rises, more tubercles degenerate and die, that is the sunflower plant expresses higher levels of resistance. (+info)Genetic relationships among Orobanche species as revealed by RAPD analysis. (3/33)
RAPD markers were used to study variation among 20 taxa in the genus OROBANCHE: O. alba, O. amethystea, O. arenaria, O. ballotae, O. cernua, O. clausonis, O. cumana, O. crenata, O. densiflora, O. foetida, O. foetida var. broteri, O. gracilis, O. haenseleri, O. hederae, O. latisquama, O. mutelii, O. nana, O. ramosa, O. rapum-genistae and O. santolinae. A total of 202 amplification products generated with five arbitrary RAPD primers was obtained and species-specific markers were identified. The estimated Jaccard's differences between the species varied between 0 and 0.864. The pattern of interspecific variation obtained is in general agreement with previous taxonomic studies based on morphology, and the partition into two different sections (Trionychon and Orobanche) is generally clear. However, the position in the dendrogram of O. clausonis did not fit this classification since it clustered with members of section TRIONYCHON: Within this section, O. arenaria was relatively isolated from the other members of the section: O. mutelii, O. nana and O. ramosa. Within section Orobanche, all O. ramosa populations showed a similar amplification pattern, whereas differences among O. crenata populations growing on different hosts were found. Orobanche foetida and O. densiflora clustered together, supporting the morphological and cytological similarities and the host preferences of these species. (+info)Micromorphological studies on seeds of orobanche species from the iberian peninsula and the balearic islands, and their systematic significance. (4/33)
BACKGROUND AND AIMS: Previous research has made clear the intrinsic taxonomic difficulties in identifying species in the genus Orobanche. The aim of this study, therefore, was to investigate the systematic utility of seed characteristics. METHODS: Light and scanning electron microscopy was used to examine the seeds of 33 taxa of Orobanche from the Iberian Peninsula and the Balearic Islands. KEY RESULTS: Characters such as size, shape and ornamentation of the seeds were not found to be very useful in differentiation of taxa; however, other characters of the epidermal seed coat cells proved to be very helpful in this respect. Ornamentation of the periclinal walls could be used to discriminate four morphological types. Other features related to the anticlinal walls of the cells, such as thickness, presence/absence of a narrow trough, or relative depth, all contributed to the characterization of a large number of species. CONCLUSIONS: The usefulness of micromorphological studies on seeds of Orobanche in relation to differentiating taxa is demonstrated, and a key is provided to distinguish species or groups of species. (+info)Isolation and characterization of a cDNA encoding phytochrome A in the non-photosynthetic parasitic plant, Orobanche minor Sm. (5/33)
In this study, the isolation and characterization of a phytochrome A (PHYA) homologous cDNA (OmPHYA) in the non-photosynthetic holoparasitic plant Orobanche minor are described. The present findings provide the first report of the presence of a PHYA homolog in the holoparasite. This study found that OmPHYA is of similar size to the other PHYAs of green plants and shows 72, 77, and 77% amino acid sequence identity with PHYA in Arabidopsis, potato, and tobacco respectively. The OmPHYA contains a conserved chromophore attachment cysteine at position 323. Although OmPHYA shows high sequence identity with other PHYAs in green plants, 13 amino acid substitutions located in both the N and C-terminal domains are observed (a total of 26 amino acids). OmPHYA is encoded by a single gene within the O. minor genome. The abundance of the OmPHYA transcript as well as nuclear translocation of OmphyA occurs in a light-dependent manner. (+info)Confirmation and quantification of strigolactones, germination stimulants for root parasitic plants Striga and Orobanche, produced by cotton. (6/33)
The germination stimulants for root parasitic plants Striga and Orobanche produced by cotton (Gossypium hirsutum L.) were examined in detail. Seeds of cotton were germinated and grown on glass wool wetted with sterile distilled water in sterile filter units. The root exudate was collected daily and extracted with ethyl acetate. Each of these ethyl acetate extracts was analyzed directly by high-performance liquid chromatography linked with tandem mass spectrometry (LC/MS/MS). The results demonstrate that cotton roots exuded strigol and strigyl acetate, but no other known strigolactones such as orobanchol and alectrol. The production of strigol was detected even in the root exudate collected during the first 24 h of incubation and reached a maximum 5-7 days later. The average exudation of strigol and strigyl acetate during the incubation period was ca. 15 and 2 pg/plant/day, respectively, indicating that strigol mainly contributed to germination stimulation by the cotton root exudate. (+info)Interaction between Orobanche crenata and its host legumes: unsuccessful haustorial penetration and necrosis of the developing parasite. (7/33)
BACKGROUND AND AIMS: Orobanche species represent major constraints to crop production in many parts of the world as they reduce yield and alter root/shoot allometry. Although much is known about the histology and effect of Orobanche spp. on susceptible hosts, less is known about the basis of host resistance to these parasites. In this work, histological aspects related to the resistance of some legumes to Orobanche crenata have been investigated in order to determine which types of resistance responses are involved in the unsuccessful penetration of O. crenata. METHODS: Samples of resistance reactions against O. crenata on different genotypes of resistant legumes were collected. The samples were fixed, sectioned and stained using different procedures. Sections were observed using a transmission light microscope and by epi-fluorescence. KEY RESULTS: Lignification of endodermal and pericycle host cells seems to prevent parasite intrusion into the root vascular cylinder at early infection stages. But in other cases, established tubercles became necrotic and died. Contrary to some previous studies, it was found that darkening at the infection site in these latter cases does not correspond to death of host tissues, but to the secretion of substances that fill the apoplast in the host-parasite interface and in much of the infected host tissues. The secretions block neighbouring host vessels. This may interfere with the nutrient flux between host and parasite, and may lead to necrosis and death of the developing parasite. CONCLUSIONS: The unsuccessful penetration of O. crenata seedlings into legume roots cannot be attributed to cell death in the host. It seems to be associated with lignification of host endodermis and pericycle cells at the penetration site. The accumulation of secretions at the infection site, may lead to the activation of xylem occlusion, another defence mechanism, which may cause further necrosis of established tubercles. (+info)A new method for in-situ monitoring of the underground development of Orobanche cumana in sunflower (Helianthus annuus) with a mini-rhizotron. (8/33)
AIMS: To develop an in-situ, non-destructive method for observation and monitoring of the underground developmental stages of the root parasite Orobanche cumana. SCOPE: The parasitic weed Orobanche causes severe damage to vegetables and field crops. Most of the damage caused to the crops occurs during the underground, unobservable parasitism stage. Sunflower (Helianthus annuus 'Adi') plants were planted in soil that was artificially inoculated with O. cumana seeds. Clear Plexiglas mini-rhizotron plastic observation tubes were inserted into the soil. Seed germination, early stage of penetration, and formation of tubercles and spikes were observed non-destructively and were monitored throughout the growing season by mean of a mini-rhizotron camera. Use of this technology enabled the complete individual parasite life cycle from the very early development (including germination) to Orobanche shoot to be monitored. In addition, the effect of the systemic herbicide Cadre (imazapic) on the development of O. cumana was inspected and quantified. CONCLUSIONS: This novel methodology facilitates the in-situ study of major aspects of the host-parasite interaction and of parasite suppression, such as parasitism dynamics, parasite growth rate, and the effect of chemical treatments on the parasite. (+info)Orobanche is not a medical term, but a genus of parasitic plants in the family Orobanchaceae. These plants are known as broomrapes and are holoparasites, meaning they rely entirely on other plants for nutrients. They have no chlorophyll and cannot photosynthesize. Instead, they tap into the roots of nearby host plants to extract water and nutrients.
While Orobanche itself is not a medical term, some species of this plant can have negative impacts on human health. For example, if these parasitic plants infect crops, they can reduce yield and quality, leading to economic losses for farmers. In addition, some people may have allergic reactions to the pollen of these plants. However, it's important to note that direct contact with Orobanche plants is unlikely to cause any significant health problems for most people.
'Striga' is not a term commonly used in medical definitions. It is actually a genus of parasitic plants, also known as witchweeds, that can cause significant damage to crops and lead to agricultural losses, particularly in Africa.
However, if you are referring to 'Striae', it is a medical term that describes linear or curvilinear grooves or furrows on the skin surface. These depressions can be either shallow or deep and may have various causes, such as scratch marks, healing processes of dermatological conditions, or underlying medical disorders.
Medical definitions typically focus on the relevance of a term to medical practice, and I'm not sure if there is a specific medical definition for "plant exudates." However, in a broader context, plant exudates refer to the various substances that are released or exuded by plants, often as a result of damage or stress. These can include a wide variety of compounds, such as sap, resins, latex, gums, essential oils, and tannins. Some of these compounds can have medicinal properties and are used in various forms of traditional and modern medicine. For example, the resin from certain pine trees (rosin) has been used to treat respiratory ailments, while willow bark, which contains salicin (a precursor to aspirin), has been used for pain relief for centuries.
In the context of medical terminology, "germination" is not typically used as a term to describe a physiological process in humans or animals. It is primarily used in the field of botany to refer to the process by which a seed or spore sprouts and begins to grow into a new plant.
However, if you are referring to the concept of germination in the context of bacterial or viral growth, then it could be defined as:
The process by which bacteria, viruses, or other microorganisms become active and start to multiply, often after a period of dormancy or latency. This can occur when the microorganisms encounter favorable conditions, such as moisture, warmth, or nutrients, that allow them to grow and reproduce. In medical contexts, this term is more commonly used in relation to infectious diseases caused by these microorganisms.
A plant root is not a medical term per se, but it is a term from botany, which is the study of plants. However, I can certainly provide a definition for you.
Plant roots are the underground organs of a plant that typically grow downward into the soil. They serve several important functions, including:
1. Anchorage: Roots help to stabilize the plant and keep it upright in the ground.
2. Absorption: Roots absorb water and nutrients from the soil, which are essential for the plant's growth and development.
3. Conduction: Roots conduct water and nutrients up to the above-ground parts of the plant, such as the stem and leaves.
4. Vegetative reproduction: Some plants can reproduce vegetatively through their roots, producing new plants from root fragments or specialized structures called rhizomes or tubers.
Roots are composed of several different tissues, including the epidermis, cortex, endodermis, and vascular tissue. The epidermis is the outermost layer of the root, which secretes a waxy substance called suberin that helps to prevent water loss. The cortex is the middle layer of the root, which contains cells that store carbohydrates and other nutrients. The endodermis is a thin layer of cells that surrounds the vascular tissue and regulates the movement of water and solutes into and out of the root. The vascular tissue consists of xylem and phloem, which transport water and nutrients throughout the plant.
I'm sorry for any confusion, but "Helianthus" is not a medical term. It is the genus name for sunflowers in the family Asteraceae. Sunflowers are native to North America and are known for their large, daisy-like flowers and tall stems. They have various uses, including ornamental purposes, food (seeds and oil), and medicinal applications in some traditional systems of medicine. However, there isn't a widely accepted medical definition associated with the term "Helianthus."
"Vicia sativa" is the scientific name for a type of plant commonly known as "Spring Vetch" or "Garden Vetch." It belongs to the legume family (Fabaceae) and is native to Europe, western Asia, and northwest Africa. The plant can grow up to 1 meter tall and has pinnate leaves with 8-14 oval leaflets. Its pea-like flowers are typically pink or purple.
While "Vicia sativa" has been used in traditional medicine for various purposes, such as treating skin conditions and respiratory issues, it is not commonly recognized as a medical term or treatment in modern Western medicine. As with any plant or herbal remedy, it's essential to consult a healthcare professional before using it for medicinal purposes, especially if you have pre-existing health conditions or are taking medications.
"Trifolium" is not a medical term. It is actually the genus name for a group of plants commonly known as clover. These plants belong to the family Fabaceae and are found in many temperate regions around the world. Some species, like red clover (Trifolium pratense), are used in herbal medicine for various purposes, such as treating respiratory conditions, skin inflammations, and menopausal symptoms. However, it's important to consult with a healthcare professional before using any herbal remedies.
Lactones are not a medical term per se, but they are important in the field of pharmaceuticals and medicinal chemistry. Lactones are cyclic esters derived from hydroxy acids. They can be found naturally in various plants, fruits, and some insects. In medicine, lactones have been used in the synthesis of drugs, including certain antibiotics and antifungal agents. For instance, the penicillin family of antibiotics contains a beta-lactone ring in their structure, which is essential for their antibacterial activity.
Autotrophic processes refer to the ability of certain organisms, known as autotrophs, to synthesize their own organic nutrients from inorganic substances using light or chemical energy. This process is essential for the production of organic matter and the formation of the basis of food chains in ecosystems.
In autotrophic processes, organisms use energy to convert carbon dioxide into organic compounds, such as glucose, through a series of metabolic reactions known as carbon fixation. There are two main types of autotrophic processes: photosynthesis and chemosynthesis.
Photosynthesis is the process used by plants, algae, and some bacteria to convert light energy from the sun into chemical energy in the form of organic compounds. This process involves the use of chlorophyll and other pigments to capture light energy, which is then converted into ATP and NADPH through a series of reactions known as the light-dependent reactions. These energy carriers are then used to power the Calvin cycle, where carbon dioxide is fixed into organic compounds.
Chemosynthesis, on the other hand, is the process used by some bacteria to convert chemical energy from inorganic substances, such as hydrogen sulfide or methane, into organic compounds. This process does not require light energy and typically occurs in environments with limited access to sunlight, such as deep-sea vents or soil.
Overall, autotrophic processes are critical for the functioning of ecosystems and the production of food for both plants and animals.
Host-parasite interactions refer to the relationship between a parasitic organism (the parasite) and its host, which can be an animal, plant, or human body. The parasite lives on or inside the host and derives nutrients from it, often causing harm in the process. This interaction can range from relatively benign to severe, depending on various factors such as the species of the parasite, the immune response of the host, and the duration of infection.
The host-parasite relationship is often categorized based on the degree of harm caused to the host. Parasites that cause little to no harm are called commensals, while those that cause significant damage or disease are called parasitic pathogens. Some parasites can even manipulate their hosts' behavior and physiology to enhance their own survival and reproduction, leading to complex interactions between the two organisms.
Understanding host-parasite interactions is crucial for developing effective strategies to prevent and treat parasitic infections, as well as for understanding the ecological relationships between different species in natural ecosystems.
In medical terms, "seeds" are often referred to as a small amount of a substance, such as a radioactive material or drug, that is inserted into a tissue or placed inside a capsule for the purpose of treating a medical condition. This can include procedures like brachytherapy, where seeds containing radioactive materials are used in the treatment of cancer to kill cancer cells and shrink tumors. Similarly, in some forms of drug delivery, seeds containing medication can be used to gradually release the drug into the body over an extended period of time.
It's important to note that "seeds" have different meanings and applications depending on the medical context. In other cases, "seeds" may simply refer to small particles or structures found in the body, such as those present in the eye's retina.
Orobanche