title: Relationship between asparagine metabolism and protein concentration in soybean seed.
abstract: The relationship between asparagine metabolism and protein concentration was investigated in soybean seed. Phenotyping of a population of recombinant inbred lines adapted to Illinois confirmed a positive correlation between free asparagine levels in developing seeds and protein concentration at maturity. Analysis of a second population of recombinant inbred lines adapted to Ontario associated the elevated free asparagine trait with two of four quantitative trait loci determining population variation for protein concentration, including a major one on chromosome 20 (linkage group I) which has been reported in multiple populations. In the seed coat, levels of asparagine synthetase were high at 50 mg and progressively declined until 150 mg seed weight, suggesting that nitrogenous assimilates are pre-conditioned at early developmental stages to enable a high concentration of asparagine in the embryo. The levels of asparaginase B1 showed an opposite pattern, being low at 50 mg and progressively increased until 150 mg, coinciding with an active phase of storage reserve accumulation. In a pair of genetically related cultivars, ∼2-fold higher levels of asparaginase B1 protein and activity in seed coat, were associated with high protein concentration, reflecting enhanced flux of nitrogen. Transcript expression analyses attributed this difference to a specific asparaginase gene, ASPGB1a. These results contribute to our understanding of the processes determining protein concentration in soybean seed.
authors.affiliation: Department of Biology, University of Western Ontario, London, Ontario, N6A 5B7, Canada.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Pandurangan
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Pajak
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Molnar
authors.forename: Elroy R
authors.initials: ER
authors.lastname: Cober
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Dhaubhadel
authors.forename: Cinta
authors.initials: C
authors.lastname: Hernández-Sebastià
authors.forename: Werner M
authors.initials: WM
authors.lastname: Kaiser
authors.forename: Randall L
authors.initials: RL
authors.lastname: Nelson
authors.forename: Steven C
authors.initials: SC
authors.lastname: Huber
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marsolais
mesh_terms: D001215:Asparaginase / Q000235:genetics / Q000378:metabolism; D001216:Asparagine / Q000378:metabolism*; D001217:Aspartate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D018506:Gene Expression Regulation, Plant; D007178:Inbreeding; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D040641:Quantitative Trait Loci / Q000235:genetics; D019655:Quantitative Trait, Heritable; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics; D012639:Seeds / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D013025:Glycine max / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D001216:Asparagine; D001215:Asparaginase; D001217:Aspartate-Ammonia Ligase