Metabolic engineering and profiling of rice with increased lysine

Summary Lysine (Lys) is the first limiting essential amino acid in rice, a stable food for half of the world population. Efforts, including genetic engineering, have not achieved a desirable level of Lys in rice. Here, we genetically engineered rice to increase Lys levels by expressing bacterial lys...

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Bibliographic Details
Published in:Plant biotechnology journal 2013-05, Vol.11 (4), p.490-501
Main Authors: Long, Xiaohang, Liu, Qiaoquan, Chan, Manling, Wang, Qing, Sun, Samuel S. M.
Format: Article
Language:English
Subjects:
Accumulation
Amino acids
Asparagine
Aspartate kinase
Biosynthesis
Catabolism
Chromatography
Dehydrogenases
Dihydrodipicolinate synthase
E coli
Fourier transforms
Gene Expression Regulation, Plant - genetics
Gene Expression Regulation, Plant - physiology
Genes
Genetic engineering
Germination
Glutamine
Interference
Ketoglutaric acid
Kinases
Leaves
Lysine
Lysine - metabolism
Mass spectrometry
Metabolic engineering
Metabolic Engineering - methods
Metabolism
Metabolites
Metabolomics
Oryza - genetics
Oryza - metabolism
Oryza sativa
Plant growth
Plants, Genetically Modified - genetics
Plants, Genetically Modified - metabolism
Population genetics
Product development
Reductases
Rice
rice (Oryza sativa L.)
RNA-mediated interference
Scientific imaging
Seed germination
Seeds
Tobacco
Transgenic plants
World population
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Summary:Summary Lysine (Lys) is the first limiting essential amino acid in rice, a stable food for half of the world population. Efforts, including genetic engineering, have not achieved a desirable level of Lys in rice. Here, we genetically engineered rice to increase Lys levels by expressing bacterial lysine feedback‐insensitive aspartate kinase (AK) and dihydrodipicolinate synthase (DHPS) to enhance Lys biosynthesis; through RNA interference of rice lysine ketoglutaric acid reductase/saccharopine dehydropine dehydrogenase (LKR/SDH) to down‐regulate its catabolism; and by combined expression of AK and DHPS and interference of LKR/SDH to achieve both metabolic effects. In these transgenic plants, free Lys levels increased up to ~12‐fold in leaves and ~60‐fold in seeds, substantially greater than the 2.5‐fold increase in transgenic rice seeds reported by the only previous related study. To better understand the metabolic regulation of Lys accumulation in rice, metabolomic methods were employed to analyse the changes in metabolites of the Lys biosynthesis and catabolism pathways in leaves and seeds at different stages. Free Lys accumulation was mainly regulated by its biosynthesis in leaves and to a greater extent by catabolism in seeds. The transgenic plants did not show observable changes in plant growth and seed germination nor large changes in levels of asparagine (Asn) and glutamine (Gln) in leaves, which are the major amino acids transported into seeds. Although Lys was highly accumulated in leaves of certain transgenic lines, a corresponding higher Lys accumulation was not observed in seeds, suggesting that free Lys transport from leaves into seeds did not occur.
ISSN:1467-7644
1467-7652
DOI:10.1111/pbi.12037