Rn. Trethewey et T. Aprees, A MUTANT OF ARABIDOPSIS-THALIANA LACKING THE ABILITY TO TRANSPORT GLUCOSE ACROSS THE CHLOROPLAST ENVELOPE, Biochemical journal, 301, 1994, pp. 449-454
At the end of a 12-h day leaves of the mutant of Arabidopsis thaliana
L., TC265, contained 4-5 times more starch than those of the wild type
. During a subsequent 12-h night the decline in the starch content of
the leaves of the mutant was at least 50% of that of the wild-type lea
ves. Starch labelled in the light in a 30-min pulse in (CO2)-C-14 was
rapidly broken down in a subsequent 12-h chase in the dark in air in t
he leaves of both mutant and wild type. Chloroplasts from leaves of th
e wild type took up [P-32]P-i and [U-C-14]glucose at 12 and 1.6 mu mol
/h per mg of chlorophyll respectively; chloroplasts from the mutant sh
owed a similar rate for [P-32]P-i but no uptake of [U-C-14]glucose. Th
e glucose content of freshly isolated chloroplasts from the mutant was
twice that of chloroplasts from the wild type; this difference was ac
centuated when the isolated chloroplasts were incubated in the dark. S
DS/PAGE of preparations of chloroplast envelopes showed that those fro
m the mutant were deficient in a protein band of approximate molecular
mass 40 kDa. It is suggested that in mutant TC265 the primary lesion
is in a hexose transporter in the chloroplast envelope, and that this
transporter moves the products of starch breakdown that are destined f
or sucrose synthesis from the chloroplast to the cytosol.