title: Soybean seeds overexpressing asparaginase exhibit reduced nitrogen concentration.
abstract: 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.
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada.|Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Pandurangan
authors.affiliation: Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Pajak
authors.affiliation: Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Tara
authors.initials: T
authors.lastname: Rintoul
authors.affiliation: Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Ronald
authors.initials: R
authors.lastname: Beyaert
authors.affiliation: Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Cinta
authors.initials: C
authors.lastname: Hernández-Sebastià
authors.affiliation: Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Daniel C W
authors.initials: DCW
authors.lastname: Brown
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada.|Genomics and Biotechnology, Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, London, Ontario, N5V 4T3, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marsolais