title: Effect of nitrogen and phosphorus deficiency on transcriptional regulation of genes encoding key enzymes of starch metabolism in duckweed (Landoltia punctata).
abstract: The production of starch by plants influences their use as biofuels. Nitrogen (N) and phosphorus (P) regulate starch gene expression during plant growth and development, yet the role of key enzymes such as ADP-glucose pyrophosphorylase (E.C. 2.7.7.27 AGPase) in starch metabolism during N- and P-deficiency remains unknown. We investigated the effect of N- and P-deficiency on the expression of large (LeAPL1, LeAPL2, and LeAPL3) and small (LeAPS) subunits of AGPase in duckweed (Landoltia punctata) and their correlation with starch content. We first isolated the full-length cDNA encoding LeAPL1 (GenBank Accession No. KJ603244) and LeAPS (GenBank Accession No. KJ603243); they contained open reading frames of 1554 bp (57.7-kDa polypeptide of 517 amino acids) and 1578 bp (57.0 kDa polypeptide of 525 amino acids), respectively. Real-time PCR analysis revealed that LeAPL1 and LeAPL3 were highly expressed during early stages of N-deficiency, while LeAPL2 was only expressed during late stage. However, in response to P-deficiency, LeAPL1 and LeAPL2 were upregulated during early stages and LeAPL3 was primarily expressed in the late stage. Interestingly, LeAPS was highly expressed following N-deficiency during both stages, but was only upregulated in the early stage after P-deficiency. The activities of AGPase and soluble starch synthesis enzyme (SSS EC 2.4.1.21) were positively correlated with changes in starch content. Furthermore, LeAPL3 and LeSSS (SSS gene) were positively correlated with changes in starch content during N-deficiency, while LeAPS and LeSSS were correlated with starch content in response to P-deficiency. These results elevate current knowledge of the molecular mechanisms underlying starch synthesis.
authors.affiliation: School of Basic Medical Sciences, Guiyang Medical University, 550000 Guiyang, Guizhou, China; Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life Sciences, Sichuan University, 610064 Chengdu, Sichuan, China; Chengdu Institute of Biology, Chinese Academy of Sciences, 610064 Chengdu, Sichuan, China. Electronic address: zhaozhao2005001@163.com.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: School of Basic Medical Sciences, Guiyang Medical University, 550000 Guiyang, Guizhou, China. Electronic address: shihuijuan0305@163.com.
authors.forename: Hui-Juan
authors.initials: HJ
authors.lastname: Shi
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life Sciences, Sichuan University, 610064 Chengdu, Sichuan, China. Electronic address: mlwang305@163.com.
authors.forename: Mao-Lin
authors.initials: ML
authors.lastname: Wang
authors.affiliation: Livzon Pharmaceutical Group Co., Ltd, Zhuhai, Guangdong, China. Electronic address: 2304732571@qq.com.
authors.forename: Long
authors.initials: L
authors.lastname: Cui
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, 610064 Chengdu, Sichuan, China. Electronic address: zhaohai@cib.ac.cn.
authors.forename: Hai
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education, College of Life Sciences, Sichuan University, 610064 Chengdu, Sichuan, China. Electronic address: zhaoyun@scu.edu.cn.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D029064:Araceae / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000172:deficiency*; D010758:Phosphorus / Q000172:deficiency*; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D021122:Protein Subunits; D010758:Phosphorus; D013213:Starch; D051599:Glucose-1-Phosphate Adenylyltransferase; D009584:Nitrogen
keywords: Deficiency; Enzyme; Expression; Nitrogen; Phosphorus; Starch