title: Effect of high temperature on grain filling period, yield, amylose content and activity of starch biosynthesis enzymes in endosperm of basmati rice.
abstract: BACKGROUND
  High temperature during grain filling affects yield, starch amylose content and activity of starch biosynthesis enzymes in basmati rice. To investigate the physiological mechanisms underpinning the effects of high temperature on rice grain, basmati rice was grown under two temperature conditions - 32 and 22 °C - during grain filling.
  
  
  RESULTS
  High temperature decreased the grain filling period from 32 to 26 days, reducing yield by 6%, and caused a reduction in total starch (3.1%) and amylose content (22%). Measurable activities of key enzymes involved in sucrose to starch conversion, sucrose synthase, ADP-glucose pyrophosphorylase, starch phosphorylase and soluble starch synthase in endosperms developed at 32 °C were lower than those at 22 °C compared with similar ripening stage on an endosperm basis. In particular, granule-bound starch synthase (GBSS) activity was significantly lower than corresponding activity in endosperms developing at 22 °C during all developmental stages analyzed.
  
  
  CONCLUSIONS
  Results suggest changes in amylose/amylopectin ratio observed in plants grown at 32 °C was attributable to a reduction in activity of GBSS, the sole enzyme responsible for amylose biosynthesis.
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Nisar
authors.initials: N
authors.lastname: Ahmed
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Tetlow
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Sehar
authors.initials: S
authors.lastname: Nawaz
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Ahsan
authors.initials: A
authors.lastname: Iqbal
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Mubin
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Muhammad Shah
authors.initials: MS
authors.lastname: Nawaz ul Rehman
authors.affiliation: Centre of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, 38040, Pakistan.
authors.forename: Aisha
authors.initials: A
authors.lastname: Butt
authors.affiliation: Department of Plant, Soil and Agricultural Systems, Carbondale, IL62901, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Lightfoot
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki, 710-0046, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Maekawa
mesh_terms: D000687:Amylopectin / Q000378:metabolism; D000688:Amylose / Q000096:biosynthesis* / Q000378:metabolism; D018533:Biomass; D050260:Carbohydrate Metabolism; D002523:Edible Grain / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D056625:Endosperm / Q000201:enzymology*; D005964:Glucosyltransferases / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D012275:Oryza / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D006005:Phosphorylases / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D013213:Starch / Q000096:biosynthesis; D013214:Starch Synthase / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D013213:Starch; D000688:Amylose; D000687:Amylopectin; D005964:Glucosyltransferases; D006005:Phosphorylases; C022699:sucrose synthase; D013214:Starch Synthase
keywords: amylose content; basmati rice; high temperature; starch biosynthesis