MadSci Network: Botany

Re: What is the effect of saltwater on freshwater plants (elodea)?

Date: Tue Dec 17 20:27:21 2002
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1040165385.Bt

When exposed to salt water, fresh water Elodea cells lose water, and the cell 
membrane pulls away from the cell wall. This is termed plasmolysis. The 
underlying process is diffusion of water from a higher concentration within the 
cell membrane to a lower concentration outside the cell membrane. Diffusion of 
water across a selectively permeable cell membrane is termed osmosis. The 
membrane is selectively permeable because virtually none of the salt crosses 
the membrane while the water passes freely across.

In ocean plants, the cell membrane allows salt to enter the cell and accumulate 
in the cell vacuole. This allows the cells to accumulate a higher salt 
concentration than the salt concentration in the sea water. Their cells do not 
plasmolyze. Scientists have recently isolated a single gene that allows salt to 
cross the cell membrane. When the gene was transferred into a tomato plant, it 
made the tomato salt tolerant.


Elodea Plasmolysis


Plasmolysis in Elodea Plant Cells

Gene Makes Tomatoes Tolerate Salt

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