There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
We have increased the contents of several amino acids in the seeds of Arabidopsis
thaliana by introduction of aspartate aminotransferase (AAT), an enzyme of the aspartate
biosynthetic pathway. mRNA was prepared from one-week-old seedlings of Glycine max
cv. enrei and the cDNA encoding AAT5 was isolated and linked to the CaMV35S promoter
in the plant vector pBI121. The AAT5 gene encodes a protein of 462 amino acid residues
that shows 51% amino acid sequence similarity to A. thaliana chloroplast Asp3. The
soybean AAT5 also contains a chloroplast transit peptide and is able to functionally
complement a Saccharomyces cerevisiae mutant lacking the Asp5 gene. A. thaliana was
transformed with the AAT5 gene from Agrobacterium tumefaciens by the vacuum infiltration
method. The AAT5 gene was detected in the transcript and genomic DNA from the transgenic
T2 plants. The T3 progeny showed a 3:1 segregation ratio indicating the presence of
a single integration. Expression of G. max AAT5 in A. thaliana transformants caused
3-, 4-, 23-, and 50-fold increases in the contents of free glycine, alanine, asparagine,
and glutamine, respectively, in the T3 seeds. A decrease in the contents of valine,
tyrosine, isoleucine, leucine, and phenylalanine by several folds was also observed.
Thus, it is of interest that a key gene expression resulted in marked changes of metabolites
in plant seeds.