CARBOHYDRATE-MODULATED GENE-EXPRESSION IN PLANTS

Plant gene responses to changing carbohydrate status can vary markedly . Some genes are induced, some are repressed, and others are minimally affected. As in microorganisms, sugar-sensitive plant genes are part of an ancient system of cellular adjustment to critical nutrient avail ability. However, in multicellular plants, sugar-regulated expression also provides a mechanism for control of resource distribution among t issues and organs. Carbohydrate depletion upregulates genes for photos ynthesis, remobilization, and export, while decreasing mRNAs for stora ge and utilization. Abundant sugar levels exert opposite effects throu gh a combination of gene repression and induction. Long-term changes i n metabolic activity, resource partitioning, and plant form result. Se nsitivity of carbohydrate-responsive gene expression to environmental and developmental signals further enhances its potential to aid acclim ation. The review addresses the above from molecular to whole-plant le vels and considers emerging models for sensing and transducing carbohy drate signals to responsive genes.