1. Improvement of pea biomass and seed productivity by simultaneous increase of phloem and embryo loading with amino acids.
- Author
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Zhang L, Garneau MG, Majumdar R, Grant J, and Tegeder M
- Subjects
- Biological Transport, Biomass, Carbon metabolism, Fruit genetics, Fruit growth & development, Fruit metabolism, Gene Expression Regulation, Plant, Nitrogen metabolism, Pisum sativum genetics, Pisum sativum metabolism, Phloem genetics, Phloem metabolism, Plant Leaves genetics, Plant Leaves growth & development, Plant Leaves metabolism, Plant Proteins genetics, Plant Proteins metabolism, Plant Proteins physiology, Plant Roots genetics, Plant Roots growth & development, Plant Roots metabolism, Plants, Genetically Modified metabolism, Seeds genetics, Seeds growth & development, Seeds metabolism, Amino Acids metabolism, Pisum sativum growth & development
- Abstract
The development of sink organs such as fruits and seeds strongly depends on the amount of nitrogen that is moved within the phloem from photosynthetic-active source leaves to the reproductive sinks. In many plant species nitrogen is transported as amino acids. In pea (Pisum sativum L.), source to sink partitioning of amino acids requires at least two active transport events mediated by plasma membrane-localized proteins, and these are: (i) amino acid phloem loading; and (ii) import of amino acids into the seed cotyledons via epidermal transfer cells. As each of these transport steps might potentially be limiting to efficient nitrogen delivery to the pea embryo, we manipulated both simultaneously. Additional copies of the pea amino acid permease PsAAP1 were introduced into the pea genome and expression of the transporter was targeted to the sieve element-companion cell complexes of the leaf phloem and to the epidermis of the seed cotyledons. The transgenic pea plants showed increased phloem loading and embryo loading of amino acids resulting in improved long distance transport of nitrogen, sink development and seed protein accumulation. Analyses of root and leaf tissues further revealed that genetic manipulation positively affected root nitrogen uptake, as well as primary source and sink metabolism. Overall, the results suggest that amino acid phloem loading exerts regulatory control over pea biomass production and seed yield, and that import of amino acids into the cotyledons limits seed protein levels., (© 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.)
- Published
- 2015
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