title: Sugar starvation- and GA-inducible calcium-dependent protein kinase 1 feedback regulates GA biosynthesis and activates a 14-3-3 protein to confer drought tolerance in rice seedlings.
abstract: Germination followed by seedling growth constitutes two essential steps in the initiation of a new life cycle in plants, and in cereals, completion of these steps is regulated by sugar starvation and the hormone gibberellin. A calcium-dependent protein kinase 1 gene (OsCDPK1) was identified by differential screening of a cDNA library derived from sucrose-starved rice suspension cells. The expression of OsCDPK1 was found to be specifically activated by sucrose starvation among several stress conditions tested as well as activated transiently during post-germination seedling growth. In gain- and loss-of-function studies performed with transgenic rice overexpressing a constitutively active or RNA interference gene knockdown construct, respectively, OsCDPK1 was found to negatively regulate the expression of enzymes essential for GA biosynthesis. In contrast, OsCDPK1 activated the expression of a 14-3-3 protein, GF14c. Overexpression of either constitutively active OsCDPK1 or GF14c enhanced drought tolerance in transgenic rice seedlings. Hence, our studies demonstrated that OsCDPK1 transduces the post-germination Ca(2+) signal derived from sugar starvation and GA, refines the endogenous GA concentration and prevents drought stress injury, all essential functions to seedling development at the beginning of the life cycle in rice.
authors: Department of Agronomy, National Chiayi University, Chiayi, 600, Taiwan, ROC. slho@mail.ncyu.edu.tw
authors: Shin-Lon
authors: SL
authors: Ho
authors: Li-Fen
authors: LF
authors: Huang
authors: Chung-An
authors: CA
authors: Lu
authors: Siou-Luan
authors: SL
authors: He
authors: Chun-Chin
authors: CC
authors: Wang
authors: Sheng-Ping
authors: SP
authors: Yu
authors: Jychian
authors: J
authors: Chen
authors: Su-May
authors: SM
authors: Yu
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D002241:Carbohydrates / Q000172:deficiency*; D055864:Droughts; D004790:Enzyme Induction / Q000187:drug effects; D025461:Feedback, Physiological / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000096:biosynthesis* / Q000494:pharmacology; D006720:Homozygote; D008954:Models, Biological; D009929:Organ Size / Q000187:drug effects; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D036226:Seedlings / Q000033:anatomy & histology / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D048948:14-3-3 Proteins; D002241:Carbohydrates; D005875:Gibberellins; D010940:Plant Proteins; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases