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Assignment 7: Revised Wikipedia Assignment 12-7-15
Link to edited page: Mimosa pudica

Description

The roots of Mimosa pudica create carbon disulfide, which prevents certain pathogenic and mycorrhizal fungi from growing within the plant’s rhizosphere. This allows the formation of nodules on the roots of the plant that contain endosymbiotic diazotrophs, which fix atmospheric nitrogen and convert it into a form that is usable by the plant.

(New Section) Nitrogen fixation

Nitrogen is a vital chemical element for both plant growth and reproduction. Nitrogen is also essential for plant photosynthesis because it is a chemical component of chlorophyll. Nitrogen fixation contributes to the nitrogen levels within the plant and adds nitrogen to the soil surrounding the plant's roots.

Mimosa pudica’s ability to fix nitrogen may have arisen in conjunction with the evolution of nitrogen-fixing bacteria. Nitrogen fixation is an adaptive trait that has transformed the parasitic relationship between the bacteria and plants into a mutualistic relationship. The shifting dynamics of this relationship are demonstrated by the corresponding improvement of various symbiotic characteristics in both Mimosa pudica and bacteria. These traits include enhanced “competitive nodulation, nodule development, intracellular infection, and bacteroid persistence”. As much as 60% of the nitrogen found in Mimosa pudica can be attributed to the fixation of N2 by bacteria. Burkholderia phymatum STM815T and Cupriavidus taiwanensis LMG19424T are beta-rhizobial strains of diazotrophs that are highly effective at fixing nitrogen when coupled with M. pudica. Burkholderia is also shown to be a strong symbiont of Mimosa pudica in nitrogen-poor soils in regions like Cerrado and Caatinga.

Cultivation

Mimosa pudica grows most effectively in nutrient poor soil that allows for substantial water drainage. However, this plant is also shown to grow in scalped and eroded subsoils. Typically, disrupted soil is necessary in order for M. pudica to become established in an area. Additionally, the plant is shade intolerant and frost-sensitive, meaning that it does not tolerate low levels of light or cold temperatures. Mimosa pudica does not compete for resources with larger foliage or forest canopy undergrowth.

Chemical constituents

Mimosa pudica demonstrates both antioxidant and antibacterial properties. This plant has also been demonstrated to be non-toxic in brine shrimp lethality tests, which suggests that M. pudica has low levels of toxicity. Chemical analysis has shown that Mimosa pudica contains various compounds, including “alkaloids, flavonoid C-glycosides, sterols, terenoids, tannins, and fatty acids”. The roots of the plant have been shown to contain up to 10% tannin. A substance similar to adrenaline has been found within the plant's leaves. Mimosa pudica 's seeds produce mucilage made up of d-glucuronic acid and d-xylose. Additionally, extracts of M. pudica have been shown to contain crocetin-dimethylester, tubulin, and green-yellow fatty oils. A new class of phytohormone turgorines, which are derivatives of gallic acid 4-O-(β-D-glucopyranosyl-6'-sulfate), have been discovered within the plant.

The nitrogen fixing properties of Mimosa pudica contribute to a high nitrogen content within the plant’s leaves. The leaves of M. pudica also contain a wide range of carbon to mineral content, as well as, a large variation in 13C values. The correlation between these two numbers suggests that significant ecological adaptation has occurred among the varieties of M. pudica in Brazil.