FEEDBACK-CONTROL OF GENE-EXPRESSION

Although feedback regulation of photosynthesis by carbon metabolites h as long been recognized and investigated, its underlying molecular mec hanisms remain unclear. The recent discovery that glucose and acetate trigger global repression of maize photosynthetic gene transcription p rovides the first direct evidence that a fundamental mechanism is used for feedback regulation of photosynthesis in higher plants. The metab olic repression of photosynthetic genes has now been found in many hig her plants and is likely universal. It overrides other regulation by l ight, tissue type and developmental stage, and serves potentially as t he molecular basis of interactions between sink and source tissues. Us ing simplified and convenient cellular systems and transgenic plants, the study of metabolic regulation of gene expression offers an excelle nt opportunity for the understanding of global and coordinate gene con trol and metabolite-mediated signal transduction in higher plants.