title: CO2-responsive CONSTANS, CONSTANS-like, and time of chlorophyll a/b binding protein Expression1 protein is a positive regulator of starch synthesis in vegetative organs of rice.
abstract: A unique CO2-Responsive CONSTANS, CONSTANS-like, and Time of Chlorophyll a/b Binding Protein1 (CCT) Protein (CRCT) containing a CCT domain but not a zinc finger motif is described, which is up-regulated under elevated CO2 in rice (Oryza sativa). The expression of CRCT showed diurnal oscillation peaked at the end of the light period and was also increased by sugars such as glucose and sucrose. Promoter β-glucuronidase analysis showed that CRCT was highly expressed in the phloem of various tissues such as leaf blade and leaf sheath. Overexpression or RNA interference knockdown of CRCT had no appreciable effect on plant growth and photosynthesis except that tiller angle was significantly increased by the overexpression. More importantly, starch content in leaf sheath, which serves as a temporary storage organ for photoassimilates, was markedly increased in overexpression lines and decreased in knockdown lines. The expressions of several genes related to starch synthesis, such as ADP-glucose pyrophospholylase and α-glucan phospholylase, were significantly changed in transgenic lines and positively correlated with the expression levels of CRCT. Given these observations, we suggest that CRCT is a positive regulator of starch accumulation in vegetative tissues, regulating coordinated expression of starch synthesis genes in response to the levels of photoassimilates.
authors.affiliation: Laboratory of Crop Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Ryutaro
authors.identifier: http://orcid.org/0000-0003-3016-9504
authors.initials: R
authors.lastname: Morita
authors.affiliation: Laboratory of Crop Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Sugino
authors.affiliation: Laboratory of Crop Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hatanaka
authors.affiliation: Laboratory of Crop Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Misoo
authors.affiliation: Laboratory of Crop Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan fukayama@people.kobe-u.ac.jp.
authors.forename: Hiroshi
authors.identifier: http://orcid.org/0000-0002-3466-8899
authors.initials: H
authors.lastname: Fukayama
mesh_terms: D000245:Adenosine Diphosphate Glucose / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D012275:Oryza / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D052585:Phloem / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D006005:Phosphorylases / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D002245:Carbon Dioxide; D000245:Adenosine Diphosphate Glucose; C037184:chlorophyll b; D013213:Starch; D006005:Phosphorylases; D051599:Glucose-1-Phosphate Adenylyltransferase; D005966:Glucuronidase; D000077194:Chlorophyll A