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Ectopic expression of phosphoenolpyruvate carboxylase in Vicia narbonensis seeds: effects of improved nutrient status on seed maturation and transcriptional regulatory networks
Author(s) -
Radchuk Ruslana,
Radchuk Volodymyr,
Götz KlausPeter,
Weichert Heiko,
Richter Andreas,
Emery R.J. Neil,
Weschke Winfriede,
Weber Hans
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03196.x
Subject(s) - phosphoenolpyruvate carboxylase , biology , abscisic acid , biochemistry , downregulation and upregulation , protein degradation , microbiology and biotechnology , metabolism , photosynthesis , gene
Summary Seed maturation responds to endogenous and exogenous signals like nutrient status, energy and hormones. We recently showed that phosphoenolpyruvate carboxylase (PEPC) overexpression in Vicia narbonensis seeds alters seed metabolism and channels carbon into organic acids, resulting in greater seed storage capacity and increased protein content. Thus, these lines represent models with altered sink strength and improved nutrient status. Here we analyse seed developmental and metabolic parameters, and C/N partitioning in these seeds. Transgenic embryos take up more carbon and nitrogen. Changes in dry to FW ratio, seed fill duration and major seed components indicate altered seed development. Array‐based gene expression analysis of embryos reveals upregulation of seed metabolism, especially during the transition phase and at late maturation, in terms of protein storage and processing, amino acid metabolism, primary metabolism and transport, energy and mitochondrial activity, transcriptional and translational activity, stress tolerance, photosynthesis, cell proliferation and elongation, signalling and hormone action and regulated protein degradation. Stimulated cell elongation is in accordance with upregulated signalling pathways related to gibberellic acid/brassinosteroids. We discuss that activated organic and amino acid production leads to a wide‐range activation of nitrogen metabolism, including the machinery of storage protein synthesis, amino acid synthesis, protein processing and deposition, translational activity and the methylation cycle. We suggest that α‐ketoglutarate (α‐KG) and/or oxalacetate provide signals for coordinate upregulation of amino acid biosynthesis. Activation of stress tolerance genes indicates partial overlap between nutrient, stress and abscisic acid (ABA) signals, indicating a common interacting or regulatory mechanism between nutrients, stress and ABA. In conclusion, analysis of PEPC overexpressing seeds identified pathways responsive to metabolic and nutrient control on the transcriptional level and its underlying signalling mechanisms.