May regulate multiple metabolic, hormonal and stress-related pathways. Required for carbohydrate metabolism and homoeostasis. May also monitor ethylene biosynthesis and senescence. Drastically altered morphogenesis, growth and development, including severe dwarfism, lancet-shaped leaves, early senescence and flower sterility. Strongly modified carbohydrate metabolism leading to increased accumulation of endogenous sugars (e.g. trehalose, trehalose-6-phosphate and starch). Ethylene over-production. Up-regulation of genes involved in sugar metabolism, senescence, ethylene biosynthesis and abiotic stress. In light, hypersensitivity to sucrose and glucose during vegetative growth, with partial phenotypic reversion in the presence of high sorbitol concentrations. Altered sugar-mediated hypocotyl elongation response in the dark. Belongs to the HEATR5 family.