MadSci Network: Botany

Re: Are Watermelons white on the inside before they are cut?

Date: Sun Feb 1 16:42:42 2004
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1075644134.Bt

That is an interesting story but totally untrue. Watermelon fruit contains 
oxygen before it is cut open because all plant cells conduct cellular 
respiration, which requires oxygen. 

The red pigment in watermelon is lycopene, the same carotenoid found in red 
tomatoes, guava and red grapefruit. Lycopene is an antioxidant, so is very 
popular as a diet supplement. Possibly this antioxidant function led to the 

Plants with symbiotic nitrogen fixation, such as beans, peas and soybeans, 
contain leghemoglobin in root nodules. The leghemoglobin keeps the oxygen 
level in the nodule very low. The enzyme nitrogenase requires a low oxygen 
environment for proper functioning. Leghemoglobin also provides oxygen to the 
nitrogen-fixing bacteria. The nodules are red or pink when you cut them open 
because of the leghemoglobin.


Watermelons and Lycopene


Re: What do Fabaceae do with the oxygen they bind in symbiotic nitrogen 

Photo of pink root nodule

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