Is there starch in the leaves of photosynthetic plants?

Question

By my understanding, a plant transports the starch it creates into the root system. Is there starch in the leaves as well? And if so, what is the purpose of containing starch in the leaves?

Answer 1

yes, a plant transports the starch it creates into the root system
Leaves are nature's food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into glucose. Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The way plants turn water and carbon dioxide into sugar is called photosynthesis. That means "putting together with light." A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is what gives plants their green color.
Soybean plants (Glycine max [L.] Merr. cv Williams), which were symbiotic with Bradyrhizobium japonicum, and which grew well upon reduced nitrogen supplied solely through N2 fixation processes, often exhibited excess accumulation of starch and sucrose and diminished soluble protein in their source leaves. Nitrate and ammonia, when supplied to the nodulated roots of N2-fixing plants, mediated a reduction of foliar starch accumulation and a corresponding increase in soluble protein in the source leaves. This provided an opportunity to examine the potential metabolic adjustments by which NO3− and NH4+ (N) sufficiency or deficiency exerted an influence upon soybean leaf starch synthesis. When compared with soybean plants supplied with N, elevated starch accumulation was focused in leaf palisade parenchyma tissue of N2-fixing plants. Foliar activities of starch synthesis pathway enzymes including fructose-1,6-bisphosphate phosphatase, phosphohexoisomerase, phosphoglucomutase (PGM), as well as adenosine diphosphate glucose pyrophosphorylase (in some leaves) exhibited highest activities in leaf extracts of N2-fixing plants when expressed on a leaf protein basis. This was interpreted to mean that there was an adaptation of these enzyme activities in the leaves of N2-fixing plants, and this contributed to an increase in starch accumulation. Another major causal factor associated with increased starch accumulation was the elevation in foliar levels of fructose-6-phosphate, glucose-6-phosphate, and glucose-1-phosphate (G1P), which had risen to chloroplast concentrations considerably in excess of the Km values for their respective target enzymes associated with starch synthesis, e.g. elevated G1P with respect to adenosine diphosphate glucose pyrophosphorylase (ADPG-PPiase) binding sites. The cofactor glucose-1,6-bisphosphate (G1,6BP) was found to be obligate for maximal PGM activity in soybean leaf extracts of N2-fixing as well as N-supplemented plants, and G1,6BP levels in N2-fixing plant leaves was twice that of levels in N-supplied treatments. However the concentration of chloroplastic G1,6BP in illuminated leaves was computed to be saturating with respect to PGM in both N2-fixing and N-supplemented plants. This suggested that the higher level of this cofactor in N2-fixing plant leaves did not confer any higher PGM activation and was not a factor in higher starch synthesis rates. Relative to plants supplied with NO3− and NH4+, the source leaf glycerate-3-phosphate (3-PGA) and orthophosphate (Pi) concentrations in leaves of N2-fixing plants were two to four times higher. Although Pi is a physiological competitive inhibitor of leaf chloroplast ADPG-PPiase, and hence, starch synthesis, elevated chloroplast 3-PGA levels in N2-fixing plant leaves apparently prevented interference of Pi with ADPG-PPiase catalysis and starch synthesis.
Recognize sugar as a product of photosynthesis and starch as 1.the method by which the plant stores energy.

Use Lugol’s Iodine Reagent as an indicator for starch.
Explain that while sugar is a product of photosynthesis, it is stored in the leaf as starch. Share with the students that starch can be detected using Lugol’s Iodine Reagent. Demonstrate the detection of starch using a slice of potato, something that the students identify as being “starchy.”

Give each group a leaf that has been partially covered for the past two days and one from the same plant that was not covered. Students should sketch each leaf in their notebooks, illustrating where on the leaf the foil or paper is positioned.

Answer 2

Yes. In form one science at school we tested for starch in leaves by boiling them in water to extract some, then adding tincture of iodine; a brown solution of iodine in alcohol, used to sterilise wounds. In the presence of starch it turns purple. Try it. You're right about the starch being transported to the roots, but it's a continuous process; starch is being produced as fast as it's removed, so there's always some in the leaves.

Answer 3

YES THERE IS STARCH IN LEAVES AS WELL