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Soybean seeds overexpressing asparaginase exhibit reduced nitrogen concentration
Author(s) -
Pandurangan Sudhakar,
Pajak Agnieszka,
Rintoul Tara,
Beyaert Ronald,
HernándezSebastià Cinta,
Brown Daniel C. W.,
Marsolais Frédéric
Publication year - 2015
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12341
Subject(s) - asparagine , asparaginase , transgene , asparagine synthetase , aspartic acid , enzyme , enzyme assay , biochemistry , embryo , nitrogen , protein subunit , chemistry , complementary dna , phaseolus , amino acid , globulin , biology , microbiology and biotechnology , botany , endocrinology , lymphoblastic leukemia , organic chemistry , leukemia , gene , genetics
In soybean seed, a correlation has been observed between the concentration of free asparagine at mid‐maturation and protein concentration at maturity. In this study, a Phaseolus vulgaris K + ‐dependent asparaginase cDNA , PvAspG2 , was expressed in transgenic soybean under the control of the embryo specific promoter of the β‐subunit of β‐conglycinin. Three lines were isolated having high expression of the transgene at the transcript, protein and enzyme activity levels at mid‐maturation, with a 20‐ to 40‐fold higher asparaginase activity in embryo than a control line expressing β‐glucuronidase. Increased asparaginase activity was associated with a reduction in free asparagine levels as a percentage of total free amino acids, by 11–18%, and an increase in free aspartic acid levels, by 25–60%. Two of the lines had reduced nitrogen concentration in mature seed as determined by nitrogen analysis, by 9–13%. Their levels of extractible globulins were reduced by 11–30%. This was accompanied by an increase in oil concentration, by 5–8%. The lack of change in nitrogen concentration in the third transgenic line was correlated with an increase in free glutamic acid levels by approximately 40% at mid‐maturation.