Physiological and molecular mechanisms underlying senescence and programmed cell death

点击翻译按钮获取中文摘要

The long-term objective of this research is to gain an increased understanding of the molecular mechanisms underlying senescence and programmed cell death in plants, and of the factors that govern transition from the growth phase of development to senescence. We have shown that membrane lipid phase separations induced by fatty acid de-esterification occur early in the senescence cascade, resulting in membrane leakiness and loss of ion and metabolite gradients essential for normal cell function. We will isolate and characterize senescence-induced genes that mediate these changes in the molecular organization of membranes, and determine how their expression is regulated. We have also identified unique cytosolic lipid-protein particles that are voided from membrane surfaces as senescence progresses. We will determine how these particles are formed, and whether their formation is the basis for: 1) controlled dismantling of membranes during senescence, and 2) the capture of membrane carbon and nitrogen for translocation out of senescing tissues to developing seeds. We have also established that distinct isoforms of eukaryotic translation initiation factor 5A (eIF5A) regulate programmed cell death and plant growth. We will elucidate the molecular mechanisms underlying this regulation, and determine whether modulation of the expression of eIF5A isoforms enhances traits of agricultural importance, including the shelf life of perishable produce, tolerance to pathogens and environmental stress, and seed yield. Results from these studies will enhance our understanding of plant senescence & growth, & may lead to the development of agronomically important technology.