title: Structure of Arabidopsis leaf starch is markedly altered following nocturnal degradation.
abstract: Little is known about the thermal properties and internal molecular structure of transitory starch. In this study, granule morphology, thermal properties, and the cluster structure of Arabidopsis leaf starch at beginning and end of the light period were explored. The structural properties of building blocks and clusters were evaluated by using diverse chromatographic techniques. On the granular level, starch from end of day had larger granule size, thinner crystalline lamellae thickness, lower free surface energy of crystals, and lower tendency to retrograde than that from end of night. On the molecular level, the starch had lower amylose content, larger cluster size, and higher number of blocks per cluster at the end of day than at end of night. It is concluded that the core of the granules contains a more permanent molecular and less-ordered physical structure different from the transitory layers laid down around the core at daytime.
authors.affiliation: School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: fzhu5@yahoo.com.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhu
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave, St Paul, MN, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Bertoft
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: You
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Emes
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Tetlow
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave, St Paul, MN, USA.
authors.forename: Koushik
authors.initials: K
authors.lastname: Seetharaman
mesh_terms: D000688:Amylose / Q000737:chemistry; D017360:Arabidopsis / Q000378:metabolism* / Q000502:physiology; D002940:Circadian Rhythm; D018515:Plant Leaves / Q000737:chemistry* / Q000378:metabolism; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature
chemical_list: D013213:Starch; D000688:Amylose
keywords: Arabidopsis; Cluster; Structure; Thermal properties; Transitory starch