title: Starch Turnover and Metabolism during Flower and Early Embryo Development.
abstract: The accumulation of starch within photosynthetic tissues and within dedicated storage organs has been characterized extensively in many species, and a function in buffering carbon availability or in fueling later growth phases, respectively, has been proposed. However, developmentally regulated starch turnover within heterotrophic tissues other than dedicated storage organs is poorly characterized, and its function is not well understood. Here, we report on the characterization of starch turnover during flower, early embryo, and silique development in Arabidopsis (Arabidopsis thaliana) using a combined clearing-staining technique on whole-mount tissue. Besides the two previously documented waves of transient starch accumulation in the stamen envelope, occurring during meiosis and pollen mitosis I, we identified a novel, third wave of starch amylogenesis/amylolysis during the last stages of stamen development. To gain insights into the underlying molecular mechanisms, we analyzed publicly available microarray data, which revealed a developmentally coordinated expression of carbohydrate transport and metabolism genes during these waves of transient starch accumulation. Based on this analysis, we characterized starch dynamics in mutants affecting hexose phosphate metabolism and translocation, and identified the Glc-6-phosphate/phosphate antiporter GPT1 as the putative translocator of Glc-6-phosphate for starch biosynthesis in reproductive tissues. Based on these results, we propose a model of starch synthesis within the pollen grain and discuss the nutrient transport route feeding the embryo within the developing seed.
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland afif.hedhli@uzh.ch grossnik@botinst.uzh.ch.
authors: Afif
authors: 0000-0002-4761-3731
authors: A
authors: Hedhly
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Hannes
authors: 0000-0002-6552-4708
authors: H
authors: Vogler
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Marc W
authors: 0000-0001-9554-5318
authors: MW
authors: Schmid
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Diana
authors: D
authors: Pazmino
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Valeria
authors: V
authors: Gagliardini
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland.
authors: Diana
authors: 0000-0001-9686-1216
authors: D
authors: Santelia
authors: Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, CH-8008 Zurich, Switzerland afif.hedhli@uzh.ch grossnik@botinst.uzh.ch.
authors: Ueli
authors: 0000-0002-0522-8974
authors: U
authors: Grossniklaus
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics; D050260:Carbohydrate Metabolism / Q000235:genetics; D049109:Cell Proliferation; D003198:Computer Simulation; D015536:Down-Regulation / Q000235:genetics; D035264:Flowers / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D011058:Pollen / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000196:embryology* / Q000235:genetics; D013213:Starch / Q000378:metabolism*; D015053:Zygote / Q000166:cytology / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D013213:Starch