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Observations on chloroplast starch content and synthesis in the intertidal marine alga Codium fragile (Suringar) Hariot
Author(s) -
WILLIAMS MICHAEL L.,
COBB A. H.
Publication year - 1988
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1988.tb04164.x
Subject(s) - chloroplast , starch , plastid , amyloplast , biology , botany , photosynthesis , biochemistry , gene
SUMMARY 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/10 9 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/10 9 plastids over a range of stromal phosphate values of 0·75–1·5 μmol PO 4 /10 9 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 P 1 : PGA ratio.