Why roots of tissue cultured plants start showing chlorophyll as the medium gets spent?
Under normal growth conditions, plants make all of their own sugars via the photosynthetic process. However, in the case of tissue culture, these plant-made sugars are supplemented by adding sucrose to the growth media. Because they are provided with this extra source of energy, tissue cultured plants have to allocate fewer resources to support photosynthesis and produce less chlorophyll than normally grown plants. As a result, tissue-cultured plants have a limited photosynthetic capacity and are reliant on the sucrose made available to them in the growth media. Therefore, When this extra energy source runs out (i.e. when the media is spent) the plants are forced to make up the difference in available energy by increasing their photosynthetic capacity.
