Microbes and invasive plants

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Microbes and invasive plants

Introduction * Key Microorganisms * Interaction Mechanisms * Current Research


Interaction between microbes and invasive plants indicates two aspect: 1)invasive plants influence microbial community composition and its ecological functions as consequences of plant invasion; 2)changed or original microbial community influences the process of invasive plants as drivers of invasion process. Three key interactions are involved: plant-pathogen, plant-symbiont and plant-decomposer interaction.

Key Microorganisms

Key Microorganisms involved in the interaction of invasive plants and microbes include three main categories: parasites or pathogens, mutualists or symbionts, and saprotrophs or decomposers.

Parasites or Pathogens and Invasive Plants

Evidence of plant species-specific pathogens have been found in rhizosphere of plants[1], which lead to the application of enemy release hypothesis in pathogens in driving plant invasion. Theoretically after invasive plants occupy a new habitat, these newly established plant species tend to have less specialistic pathogens, thus they can outcompete other native plant species. However, the probability still exists that shifts of pathogens from native plants to their phylogenetic close non-native plants may confound the effects of enemy release[2].

There are some invasive plants that are able to accumulate generalist pathogens in their rhizosphere, which will in turn inhibit native vegetation grown in the habitat[3]. Empirical evidence has been found in a study about invasion success of Chromolaena odorata which suppress native plants by accumulating high concentration of pathogens in its rhizosphere, since native plants are more sensitive to these pathogens than newly established plants.[4].

Mutualists or Symbionts Invasive Plants

Two main mutualists in the soil that have a close relationship with plant invasion success: myccorhizas and nitrogen fixers. There are two ways that these microbes can facilitate plant invasion. One way is that invasive plants benefit from association with native mutualists, such as AMF(arbuscular myccorhizal fungi) and nitrogen fixers, to outcompete native plant species and change the soil properties of newly established habitat, which in turn influences native plant community. For those mutualist-dependent exotic plants, whether they will become a successful invader largely depends on whether they can find their mutualists in the invasive range[5].

The other way is that invasive plants disrupt the mutualism systems of native plants by exuding toxic chemicals to their mutualists, thus suppress native species. A typical example of this case is Alliaria petiolata, a invasive plant that inhibits AMF and ectomycorrhizal fungal colonization on which native plants depend on[6].

Saprotrophs or Decomposers and Invasive Plants

If invasive plants occupy a new range where native plants tend to have different life strategy from invasive plants, in most cases, invasive plants have acquisitive traits such as fast-growth, short-lived poorly defended tissues, and high nutrient concentrations while native plants have conservative traits such as slow growth, long-lived well-defended tissues, and low nutrient concentration, invasive plants tend to have greater influences on native decomposers by adding exotic nutrient resources to affect native saprophytic microbial community, native decomposition, native soil process, therefore influence native plant community[1].

Interaction Mechanisms

There are three main categories about how interaction of microbes and invasive plants drive their invasion success. First, invasive plants suffer less negative soil feedback than native species, or even have neutral or positive feedback[7], also known as Enemy Release hypothesis. Second, invasive plants are able to disturb newly established habitat by enhancing pathogen levels or destructing symbionts systems, thus suppress native plants while invaders suffer less from this, which involves Accumulation of Local Pathogens hypothesis[3]. Third, allelochemicals can play an important role in helping exotic plants establishing invaded habitats. These chemicals hard to be detoxified by local microbial community can easily reach toxic level therefore harm native plant species, also known as Novel Weapons hypothesis[8].


[1] van der putten, 2007 [2]Reinhart, 2006 [3]Eppinga, 2006 [4]Mangla, 2008 [5]Mitchell,2006 [6]Callaway, 2008 [7]Klironomos,2002

Viral Biorealm: encyclopedia of viruses of animals and plants, and bacteriophages. See also Taxonomy Index.
Microbial Mythology: common misconceptions and controversies in microbiology.

Managing Editor

Daniel Barich '05

Kenyon Student Editors

Kristina Buschur, '11, Ryo Tashiro '09, Molly Schlemmer '08, Shrochis Karki '09, Drew Taber3, Allison Whipple '06, Zeva Levine1, Laura Damon-Moore1, Ariel Kahrl2, Hannah Sacks '08, Michael Stulberg '05, Casey M. Smith '06, and Shana Scogin '07

Advisor: Joan Slonczewski, Biology Dept, Kenyon College
Guest editors from 1Beloit, 2Oberlin, and 3Columbia Union College.
Funded by HHMI awards to Kenyon College, 2000, 2004.

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