In the war between the sexes, the one with the closest fungal relationship winsNovember 11, 2009Female plants were more likely to be colonized by the mycorrhizal fungi than male plants The war between the sexes has been fought on many fronts throughout time-from humans to birds to insects, the animal kingdom is replete with species involved in their own skirmishes. A recent study by Dr. Sarah Eppley and colleagues at Portland State University published in the November issue of the American Journal of Botany (www.amjbot.org/cgi/content/full/96/11/1967) demonstrates that certain plants, with some help from fungal friends, may also be involved in this fray. Most flowering plants form symbiotic relationships with mycorrhizal fungi. The plants produce food that the fungi need to survive, and the fungi provide several benefits to plants. They may assist the plants in nutrient uptake, provide protection against fungal pathogens that would harm the plants' roots, and improve the soil structure. With the many benefits these mycorrhizal fungi provide to plants, they have the potential to play a significant role in shaping plant populations. Interactions between the plant and the mycorrhizal fungi may be influenced by the genetic composition of the plant. This raises the question: for species with separate male and female plants, do interactions with mycorrhizal fungi vary between the sexes and consequently play a role in the male/female structure of the population? "We know that male and female plants often differ in physiology, but little is known about whether the sexes differ in their interactions with other organisms," Eppley noted. "If males and females differ in how they interact with organisms in their community, such as with mycorrhizal fungi, then we expect a cascade of effects within a community." Eppley and colleagues analyzed mycorrhizal colonization of roots of male and female members of the marsh grass Distichlis spicata to determine whether the sex of the plant influences the interaction between the plant and mycorrhizal fungi. In populations of D. spicata, males are found almost exclusively in habitats that have a low nutrient concentration and females are found almost exclusively in habitats with a higher nutrient concentration. The relationship between D. spicata and mycorrhizal fungi is known to have a significant effect on the health and reproduction of the grass. If D. spicata exhibits sex-specific interactions with the mycorrhizal fungi, this distribution may be due to those interactions. Eppley and colleagues found differences in mycorrhizal colonization between males and females. Female plants were more likely to be colonized by the mycorrhizal fungi than male plants. Although some of the plants they studied had not yet reached reproductive maturity, these immature plants also showed the same pattern of sex-specific colonization. Intersexual competition has been hypothesized to be a likely cause of the spatial segregation of the sexes in D. spicata populations. It may be that the female plants, with the assistance of mycorrhizal fungi, are able to out-compete the male plants for the coveted phosphorous-rich sites within the marsh. "Although intersexual competition in plants has rarely been studied," said Eppley, "understanding the differences in how males and females compete is important because it is likely to play a role in the evolution of population sex ratios." American Journal of Botany |
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| Related Mycorrhizal Fungi Current Events and Mycorrhizal Fungi News Articles Professor hopes to help high elevation pines grow Thread-like fungi that grow in soils at high elevations may play an important role in restoring whitebark and limber pine forests in Canada. Reforestation using exotic plants can disturb the fertility of tropical soils In many regions of the world, the impact of human activity on the environment intensified considerably over the past century. The high world population growth rate and the expansion of areas given over to crop production associated with climatic changes (longer periods of drought, irregular rainfall patterns) induced by global warming, have contributed to the acceleration of desertification. A common genetic mechanism discovered in nitrogen-fixing plants Some soil microorganisms are capable of forging associations with plant roots in the form of symbioses. Certain of these relationships play a highly important ecological and agronomic role. Mechanisms of plant-fungi symbiosis characterized by DOE Joint Genome Institute Plants gained their ancestral toehold on dry land with considerable help from their fungal friends. Now, millennia later, that partnership is being exploited as a strategy to bolster biomass production for next generation biofuels. Hungry microbes share out the carbon in the roots of plants Sugars made by plants are rapidly used by microbes living in their roots, according to new research at the University of York, creating a short cut in the carbon cycle that is vital to life on earth. DOE JGI sequences, releases genome of symbiotic tree fungus The DNA sequence of Laccaria bicolor, a fungus that forms a beneficial symbiosis with trees and inhabits one of the most ecologically and commercially important microbial niches in North American and Eurasian forests, has been determined by the U.S. Department of Energy DOE Joint Genome Institute (DOE JGI). New Method Confirms Importance of Fungi in Arctic Nitrogen Cycle A new method to calculate the transfer of nitrogen from Arctic mushrooms to plants is shedding light on how fungi living symbiotically on plant roots transfer vital nutrients to their hosts. Invasive species harms native hardwoods by killing soil fungus An invasive weed that has spread across much of the U.S. harms native maples, ashes, and other hardwood trees by releasing chemicals harmful to a soil fungus the trees depend on for growth and survival. Soil fungi affect parasitism of foliage-feeding insects Recent studies have shown the importance of links between soil organisms and those feeding above-ground. However, to date these have involved two or three trophic levels, because it has been assumed that the effects weaken as one progresses up or down a food chain. In a forthcoming paper in Ecology Letters, Gange, Brown & Aplin show that strong interactions occur between four trophic levels. They found that symbiotic mycorrhizal fungi in the soil affect plant growth, which determined the attack rate of a leaf mining fly and in turn the rate of parasitism of the fly by a wasp. The results show that there are strong links between species in natural communities, even though those species may be An unexpected outcome of atmospheric CO2 enrichment Unseen belowground interactions impact the composition of natural plant communities. Mycorrhizae, symbiotic associations between soil fungi and plant roots, help plants acquire soil nutrients but also drain substantial carbon from plants. Whether mycorrhizae help or hinder plant growth depends upon the balance between nutrient benefits and carbon costs. Mycorrhizae can structure plant communities because they improve the growth of some plant species more than others. In the forthcoming issue of Ecology Letters, Johnson, Wolf and Koch demonstrate that enrichment of atmospheric CO2 and soil N interacts with mycorrhizae to structure the species composition of experimental plant communities. Dis More Mycorrhizal Fungi Current Events and Mycorrhizal Fungi News Articles |
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