Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.). X.* Isoflavone formation and carbohydrate metabolism

Abstract

The relationships between isoflavone formation and carbohydrate metabolism were studied in a controlled-environment experiment at low (4700 lux) and high (31,200 lux) light intensities. During expansion of the first trifoliate leaf, isoflavone contents per cell were much lower at low light supply than at high. These low isoflavone contents were associated with low contents of sugars and starch. Protein and cell walls were less affected by low light than were sugars and starch and, presumably, competed strongly with isoflavones for carbon substrates.

From the results of this and earlier controlled-environment experiments a close curvilinear relationship was obtained between isoflavones and soluble sugars per cell at the stage of full leaf expansion (when isoflavone synthesis normally ceases). Thus soluble sugar content provided a good index of the level of carbon substrates used for isoflavone synthesis. Some instances where isoflavones increase after full leaf expansion are also discussed.

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*Part IX, Aust. J. Agric. Res., 23: 411 (1972).