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Accumulation of label from radioactive precursors into dry matter by wheat endosperm cultured in vitro
Author(s) -
Millet Eitan,
Jenner Colin F.
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb02473.x
Subject(s) - endosperm , starch , sucrose , in vitro , ethanol , fraction (chemistry) , dry matter , chemistry , biochemistry , caryopsis , glutamine , food science , biology , poaceae , botany , chromatography , amino acid
The capacity of in vitro cultured common wheat ( Triticum aestivum L.) endosperms to incorporate starch and protein precursors was investigated. Isolated 2–3 week‐old endosperms were cultured up to 2 weeks in a liquid medium containing labelled ( 14 C)‐sucrose and ( 3 H)‐glutamine. Cultured endosperms were separated into ethanolsoluble, starch and protein fractions and the incorporation of the label into each of these fractions was assessed at different times after commencement of culture. The same medium was introduced through the peduncle into normally‐developing grains, which were then similarly analyzed. Accumulation of both 14 C and 3 H in the ethanol‐soluble fraction occurred, at a decreasing rate, only during the first 3 days, and then ceased. The accumulated label in the starch fraction, which originated mainly as 14 C sucrose, proceeded at a relatively constant rate for one week and reached only about 1/5 of the expected in vivo starch production. Incorporation of both isotopes into the protein fraction reflected similar utilization of sucrose and glutamine from the medium (molar base), decreasing in rate with time. Culturing beyond one week produced deteriorated endosperms. Compared to cultured endosperms, normally‐developing grains incorporated proportionally less precursors into the ethanol‐soluble and more into the insoluble fraction. It is suggested that the reduced starch and protein synthesis in cultured grains stems from impaired capacity of the biosynthetic machinery rather than from low availability of precursors.