Lawns are sometimes fertilized with nitrate that can be washed into neighboring woodlots by rain. If the trees in that woodlot are associated with EMF, what effect might the excess nitrate have on the fungi and/or trees?
a. Fungal growth may be stimulated, causing the trees to transport more nitrogen to the fungi.
b. The fungi may secrete more peptidases to break down the nitrate.
c. The trees may take up the nitrate directly into their roots and rely less on the fungi.
d. The excess nitrate may stimulate the fungi to transport more sugar to the trees.

Verified step by step guidance

1. Understand the relationship between trees and ectomycorrhizal fungi (EMF). EMF form symbiotic associations with tree roots, aiding in nutrient exchange, particularly nitrogen and phosphorus.
2. Consider how nitrate, a form of nitrogen, affects this symbiotic relationship. Trees typically rely on fungi to help absorb nutrients from the soil, but excess nitrate could alter this dynamic.
3. Evaluate option a: Excess nitrate could stimulate fungal growth, but this would likely lead to the fungi requiring more nitrogen from the trees, not the other way around.
4. Evaluate option b: Fungi secrete enzymes like peptidases to break down organic nitrogen sources, not inorganic nitrate. Therefore, this option is unlikely.
5. Evaluate option c: With excess nitrate available, trees might absorb nitrate directly through their roots, reducing their reliance on fungi for nitrogen acquisition.

Key Concepts

Ectomycorrhizal Fungi (EMF)

Ectomycorrhizal fungi (EMF) form symbiotic relationships with the roots of many tree species, enhancing nutrient uptake, particularly phosphorus and nitrogen, in exchange for carbohydrates from the host plant. This mutualistic relationship is crucial for tree health and growth, especially in nutrient-poor soils. Understanding EMF is essential to predict how external factors like excess nitrate might alter this balance.

Nitrate Uptake in Plants

Nitrate is a vital nitrogen source for plants, absorbed directly through their roots. In environments with high nitrate availability, plants may reduce their reliance on symbiotic fungi for nitrogen, potentially altering the dynamics of mutualistic relationships. This concept helps explain how excess nitrate could impact the interaction between trees and EMF.

Nutrient Transport and Symbiosis

In symbiotic relationships, nutrient transport is a key process where fungi provide essential nutrients like nitrogen to plants, while plants supply carbohydrates to fungi. Changes in nutrient availability, such as increased nitrate, can shift this balance, affecting the growth and nutrient exchange rates between the symbiotic partners. Understanding this transport mechanism is crucial to assess the impact of environmental changes on symbiotic interactions.