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Conversion of Labeled Substrates to Sugars, Cell Wall Polysaccharides, and Tartaric Acid in Grape Berries
Kazumi Saito and Zenzaburo Kasai
Vol. 62, No. 2 (Aug., 1978), pp. 215-219
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/4265407
Page Count: 5
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[U-14C]Sucrose, myo-[U-14C]inositol, [6-14C]- and [U-14C]glucuronate, UDP-[U-14C]glucuronate, [U-14C]gluconate, and L-[1-14C]ascorbic acid were fed into grape berries, Vitis labrusca L. cv. Delaware, at intervals throughout the ripening process and incorporation of 14C into several metabolites was studied. [U-14C]Sucrose was the most effective precursor of cellulose in young grape berries and of glucose and fructose in mature berries. On the other hand, UDP-[U-14C]glucuronate was the best precursor of pectic substance, followed by [14C]glucuronate and myo-[U-14C]inositol. L-[1-14C]Ascorbic acid was the most effective precursor of tartaric acid. In young berries, [U-14C]sucrose and [U-14C]gluconate also produced labeled tartaric acid, the latter a somewhat better precursor in the 3 weeks following flowering. The remaining test compounds were only poor sources of 14C for tartaric acid although all three, glucuronate, UDP-glucuronate, and myo-inositol, were utilized by the grape berry for pectin biosynthesis. These results strongly indicate that tartaric acid is synthesized by a C-1 oxidation mechanism of hexose in young grape berries.
Plant Physiology © 1978 American Society of Plant Biologists (ASPB)