Gene expression of ADP-glucose pyrophosphorylase and starch contents in rice cultured cells are cooperatively regulated by sucrose and ABA.
Six cDNA clones encoding two small subunits and four large subunits of ADP-glucose pyrophosphorylase (AGPase) were mined from the database of rice full-length cDNAs, cloned and subsequently named: OsAPS1, OsAPS2, OsAPL1, OsAPL2, OsAPL3 and OsAPL4. Expression patterns of the six genes were examined by Northern blot analysis with gene-specific probes. OsAPL3 was predominantly expressed in the middle phases of seed development, and OsAPS1, OsAPL1 and OsAPL2 were expressed later in seed development. OsAPS2 and OsAPL4 were constitutively expressed and these isoforms were coordinated with starch accumulation in the developing rice seed. In order to clarify the effect of sugars and plant hormones on AGPase gene expression more precisely, a rice cell culture system was used. OsAPL3 transcript significantly accumulated in response to increased levels of sucrose and abscisic acid (ABA) concentration in the medium; however, the transcripts of other AGPase genes did not show significant accumulation. Under identical conditions, starch contents in the cultured cells also increased. Interestingly, ABA alone did not affect the gene expression of OsAPL3 and starch content. Collectively, these results indicated that the expression level of OsAPL3 and starch content in the cultured cells were cooperatively controlled by alterations in the concentration of both sucrose and ABA.
Akihiro
Takashi
T
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8572 Japan.
Mizuno
Kouichi
K
Fujimura
Tatsuhito
T
D000040:Abscisic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D051599:Glucose-1-Phosphate Adenylyltransferase; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000235:genetics*; D012275:Oryza / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology
D018076:DNA, Complementary; D018744:DNA, Plant; D010937:Plant Growth Regulators; D018749:RNA, Plant; D013395:Sucrose; D000040:Abscisic Acid; D013213:Starch; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase