Striga
Orobanche
Germination
Characterization of nitrogen relationships between Sorghum bicolor and the root-hemiparasitic angiosperm Striga hermonthica (Del.) Benth. using K15 NO3 as isotopic tracer. (1/16)
The role of the host in the nitrogen nutrition of Striga hermonthica (Del.) Benth. (Scrophulariaceae) parasitic on Sorghum bicolor cv. SH4 Arval has been investigated using (15)N-nitrate as the tracer. It is shown that, when nitrate is absorbed only by the roots of the host plant, a rapid transfer of nitrogen to the parasite can be detected. The xylem sap of S. hermonthica contained approximately equal amounts of nitrate and amino acids, mostly glutamine and asparagine. Infection altered the free amino acid profile of the host tissues, leading notably to a large increase in asparagine and a decrease in glutamine. The haustoria of S. hermonthica, although rich in nitrate, showed a low concentration of free amino acids, particularly lacking in asparagine and glutamine. The roots of S. hermonthica, in contrast, were rich in both asparagine and glutamine while, in the shoots, asparagine constituted 80% of the total FAA pool. Asparagine was also found to be the primary (15)N-enriched amino acid in the shoots of S. hermonthica while, interestingly, it was glutamate that was most strongly enriched in the roots. It is concluded that nitrogen nutrition in S. hermonthica is based on a supply of both nitrate and amino acids from the host. This implies a non-specific transfer in the transpiration stream. Nitrate reduction probably occurs mainly in the leaves of the parasite. Assimilation also occurs in S. hermonthica and excess nitrogen is stored as the non-toxic nitrogen-rich compound, asparagine. This specific trait of nitrogen metabolism of the parasite is discussed in relation to the effect of nitrogen fertilization on reducing infestation. (+info)Confirmation and quantification of strigolactones, germination stimulants for root parasitic plants Striga and Orobanche, produced by cotton. (2/16)
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)The strigolactone germination stimulants of the plant-parasitic Striga and Orobanche spp. are derived from the carotenoid pathway. (3/16)
The seeds of parasitic plants of the genera Striga and Orobanche will only germinate after induction by a chemical signal exuded from the roots of their host. Up to now, several of these germination stimulants have been isolated and identified in the root exudates of a series of host plants of both Orobanche and Striga spp. In most cases, the compounds were shown to be isoprenoid and belong to one chemical class, collectively called the strigolactones, and suggested by many authors to be sesquiterpene lactones. However, this classification was never proven; hence, the biosynthetic pathways of the germination stimulants are unknown. We have used carotenoid mutants of maize (Zea mays) and inhibitors of isoprenoid pathways on maize, cowpea (Vigna unguiculata), and sorghum (Sorghum bicolor) and assessed the effects on the root exudate-induced germination of Striga hermonthica and Orobanche crenata. Here, we show that for these three host and two parasitic plant species, the strigolactone germination stimulants are derived from the carotenoid pathway. Furthermore, we hypothesize how the germination stimulants are formed. We also discuss this finding as an explanation for some phenomena that have been observed for the host-parasitic plant interaction, such as the effect of mycorrhiza on S. hermonthica infestation. (+info)Integrated pest management: the push-pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry. (4/16)
This paper describes the 'push-pull' or 'stimulo-deterrent diversionary' strategy in relation to current and potential examples from our own experiences. The push-pull effect is established by exploiting semiochemicals to repel insect pests from the crop ('push') and to attract them into trap crops ('pull'). The systems exemplified here have been developed for subsistence farming in Africa and delivery of the semiochemicals is entirely by companion cropping, i.e. intercropping for the push and trap cropping for the pull. The main target was a series of lepidopterous pests attacking maize and other cereals. Although the area given to the cereal crop itself is reduced under the push-pull system, higher yields are produced per unit area. An important spin-off from the project is that the companion crops are valuable forage for farm animals. Leguminous intercrops also provide advantages with regard to plant nutrition and some of the trap crops help with water retention and in reducing land erosion. A major benefit is that certain intercrop plants provide dramatic control of the African witchweed (striga). Animal husbandry forms an essential part of intensive subsistence agriculture in Africa and developments using analogous push-pull control strategies for insect pests of cattle are exemplified. (+info)Synthesis and seed germination stimulating activity of some imino analogs of strigolactones. (5/16)
Strigolactones are germination stimulants for seeds of the root parasitic weeds, Striga and Orobanche spp. The imino analog of GR24 showed moderate germination stimulating activity against the seeds of S. hermonthica. The seed germination stimulating activity of some phenyliminoacetates and phenyliminoacetonitriles was also examined. The degree of activity of the phenyliminoacetate was less than that of the phenylacrylates. On the other hand, the degree of activity of the phenyliminoacetonitrile was comparable to that of the phenylacrylonitriles. Among the tested compounds, the 3-pyridyliminoacetonitrile showed higher activity against the seeds of O. crenata than GR24. These findings demonstrate that it is not always essential to have the Michael acceptor of the C-D ring junction moiety which has been proposed to react with nucleophilic species presented at the target site to enhance the activity. (+info)Strigolactones and shoot branching: a new trick for a young dog. (6/16)
(+info)Molecular responses of Lotus japonicus to parasitism by the compatible species Orobanche aegyptiaca and the incompatible species Striga hermonthica. (7/16)
(+info)Gene-for-gene resistance in Striga-cowpea associations. (8/16)
(+info)'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.
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.
Orobanchaceae is a family of flowering plants, also known as the broomrape family. These are parasitic or hemiparasitic plants, which means they derive some or all of their nutrients from other plants by attaching to their roots and tapping into their vascular systems.
The family includes both holoparasites, which are completely dependent on their host plants for nutrients, and facultative parasites, which can grow independently but benefit from parasitism.
Notable genera in this family include Striga (witchweeds), Orobanche (broomrapes), and Pedicularis (louseworts). Some members of this family can cause significant damage to agricultural crops, making them important subjects of study in the field of plant pathology.
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.
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.