Observations on chloroplast starch content and synthesis in the intertidal marine alga Codium fragile (Suringar) Hariot
1988
Williams, Michael L. | COBB, A. H.
A marked seasonal response was observed in the starch content of chloroplasts of Codium fragile sampled between November 1983 and November 1984. Chloroplast starch uniformly increased throughout the life‐cycle of this alga, reaching a maximum in the summer months of approx. 5 mg glucose equivalents/10⁹ plastids when C. fragile was in the reproductive phase. Chloroplast starch content was found to be inversely proportional to the concentration of stromal phosphate, decreasing linearly from 5 to 2 mg glucose equivalents/10⁹ plastids over a range of stromal phosphate values of 0·75–1·5 μmol PO₄/10⁹ plastids. Similarly, the net amount of starch synthesized over 3 h by isolated chloroplasts increased linearly with respect to initial chloroplast starch content. These observations are discussed in relation to the regulation of starch synthesis by variations in the stromal P₁: PGA ratio.
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