Glucose Insensitive Mutants Background Nutrient sensing and signaling is an important process to allow organisms to adjust growth and metabolism to adapt developmental and environmental changes. Carbon and nitrogen are traditionally considered as two major energy sources for plant growth and development. However, recent studies have suggested that both carbon and nitrogen are also signal molecules that are important in regulating gene expressions and a wide variety of responses.
Sugar signaling in plants is particularly complicated due to their photoautotrophic nature.
Unlike animals, plants need to coordinate the production of carbon from photosynthesis with its utilization, mobilization, and allocation in various tissues at different tissues. High sugar levels repress the expression of genes for sugar production and instead induce genes for storage and utilization. Sugar depletion exerts the opposite effects. Although important, very little is known about how sugar signal is perceived and transmitted in plants. Recently, it has become apparent that sugars affect the expression of certain genes involved in many essential processes such as photosynthesis, glycolysis, glyoxylate metabolism, nitrogen metabolism, sucrose and starch metabolism, defense mechanisms, and cell cycle regulation.