photosmynthesis's Blog

Assignment 2 Cont’d….
September 24, 2010, 6:21 am
Filed under: Uncategorized

Part 3

When thinking of transport of materials, I think about the soil.  Much of the activity at this level we can’t observe, but this is where most of the action is happening.  Plants and fungus do a huge amount of work below ground, foraging through a complex matrix of organic and inorganic materials, fighting off pathogens, and competing with other organisms for much desired commodities such as nitrogen, phosphorus, and other necessary elements for growth.  They are at the interface between the biotic and abiotic environment, and often hold the majority of the food web on their shoulders…

But what makes them able to perform this job?  Both plants and fungi are distinctly different from animals, and interestingly enough, there are some commonalities between these two.  The design that makes one most fit for this job seems to include a few simple features, for instance, high surface-area to volume ratio, great absorptive capacity, and indeterminate growth.  Both the fine roots of plants, as well as the hyphal mats of the fungal mycelium have these features, even though these two organisms are evolutionarily, very distinct.   But, these features allow for continuous excavation of new territory, with no worry about the road home (indeterminant growth).  Also they have the best possible change or reaping the benefits of these efforts (amazing absorptive capacity, and high S-A:V).  This may be one of the reasons that fungi has been traditionally taught in sections of plant biology, even though the kingdoms are quite distinct.  Nevertheless, no one can deny that many of the organisms from both of these groups occupy niches in the environment that are intimately related to each other.

The most extreme case of this association has to be mycorrhizal associations that are made by the majority of plants and fungi.  These interactions connect these two organisms, creating a mutualism that has profound implications for ecosystem function.  For the plant, the smaller diameter of the fungal hyphae can penetrate into the soil at a much finer level and over a greater distance than the fine roots of one individual.  This provides increase access to water and nutrients (Liu et al. 1999).  For the Fungus, the carbon assimilated by the plant is a steady source of metabolites for this sojourning forager.

This interaction fits together so well, and is particularly interesting that the parts of organisms are so different and yet so similar in design.  Perhaps we can use some of these features, or perhaps these organisms for harvesting substances from the earth, just as the roots and fungus do….

Liu A., Hamel C., Hamilton R.I., Ma B.L., Smith D. L. (1999) Acquisition of Cu, Zn, Mn and Fe by mycorrhizal maize ( Zea mays L.) grown in soil at different P and micronutrient levels MYCORHIZZA 9:331-336


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