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Effect of an increased sink demand on the carbon metabolism and export of a maize source leaf
Author(s) -
Jeannette Emmanuelle,
Rocher JeanPaul,
Prioul JeanLouis
Publication year - 1995
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.1399-3054.1995.tb05318.x
Subject(s) - photosynthesis , sucrose , starch , sink (geography) , carbohydrate , chemistry , carbon source , carbohydrate metabolism , metabolism , botany , horticulture , food science , biology , biochemistry , cartography , geography
The sink demand was increased on a source maize leaf ( Zea mays L. cv. F7F2) by darkening all the leaves except the fourth, which was maintained under the prevailing irradiance conditions. The parameters of carbon metabolism were measured precisely during the first hours, and then daily during one week. The ambient photosynthetic activity and the maximum photosynthetic capacity were not altered by the treatment but the soluble carbohydrate and starch contents diminished, while ADP‐glucose pyrophosphorylase (EC 2.7.7.27) activity increased. The carbon export rate, evaluated by the rate of disappearance of radioactivity after a 1‐min 14 CO 2 pulse, was faster than in control leaves. A compartmental analysis of the time course of 14 C export further indicated that the sucrose pool providing the export flux was largely increased by the dark treatment. The darkened leaf 5, taken as an example of the darkened sources, was completely depleted of its carbohydrate content after one day in the dark and remained devoid of carbohydrates during the following week.