Arbuscular Mycorrhizal Fungi

These fungi (“AMF”) colonize roots when spores germinate in the soil and grow toward roots.  They establish internal structures that allow the fungus to get photosynthetic products from the plant for their growth.  In return, external fungal structures bring nutrients from the soil into the root for the plant’s nutrition.  Most of the tree species in our project are colonized by AMF.

   

Micrographs of AMF inside roots; fungal tissues stain blue. (A) A root tip of the native tropical tree Cedrela odorata colonized by AMF.  The spheres are vesicles, which store photosynthetic products for the fungus.  Middle: arbuscule in a leek root (Division of Plant Sciences, Kings Park and Botanic Garden, Perth, Australia). Arbuscules are the site of nutrient exchange between root and fungus.  (B)  A root of Terminalia amazonia showing oblong vesicles and thread-like external hyphae.  Hyphae bring mineral nutrients from the soil into the plant.

         

Five spore types found in soil samples from our study site.  The graph shows that the number of different types of AMF spores depends on degree of erosion at each site on the farm.  Sites with the greatest erosion are rank 1, at the left of the abscissa.  Spore diversity is low in the most eroded soils, ranks 1, 2 and 3 (Carpenter et al. 2001).  Low diversity could be a problem for regeneration of many trees if tree species prefer certain AMF types.


[R.A.I.N.] [Dr. Lynn Carpenter]