Red-light effect on tracer distribution in etiolated leaf tissue.

A survey of the distribution of tracer in preparations from etiolated corn leaf sections which had been fed with uniformly labeled glucose (glucose-U-C(14)) and then exposed to ten minutes of red light, failed to show the presence of any new or specifically labelled metabolite. The earliest consequence of the light-treatment was a loss of tracer from the soluble sugars accompanied by an accumulation of C(14) in the cell-wall polysaccharides. Other light effects were reduced labelling of amino acids and higher phosphate turnover rates. The survey did not elucidate the nature of the first biochemical response after an exposure of an etiolated seedling to radiant energy, but it suggests several areas of further investigation.