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.

ASN1‐encoded asparagine synthetase in floral organs contributes to nitrogen filling in Arabidopsis seeds

“…In the CaMV35S :: ASN1 expressors, increased asparagine at stage 0–2 and improved seed yields (total nitrogen, soluble proteins, seed weight, seed number per silique) (Table ) match a positive correlation between free asparagine and seed nitrogen reported in several plant species (Lam et al ., ; Seiffert et al ., ; : Hernández‐Sebastià et al ., ; Wan et al ., ; Pandurangan et al ., ). To depict seed nitrogen filling, asparagine metabolic pathways can be divided into two phases: (i) de novo synthesis of amino acids for use in cell division and embryo differentiation from stage 0, 1 to 2 in floral organs (Figures , S1 and S3), and (ii) subsequent incorporation of amino acids into building protein blocks for morphogenesis of seed coat, endosperm and embryo from stage 4, 7 to 11 in maturing siliques (Figures , S2 and S4).…”

Structural basis of potassium activation in plant asparaginases

“…For instance, the K + -dependent asparaginases are highly expressed in developing seed coat of tropical legumes like soybean, which use asparagine as a major form in the nitrogen nutrition of the seed [27]. In the case of plant asparaginases, higher catalytic efficiency enables increased metabolic flux from asparagine under specific physiological conditions.…”

Identification of major QTLs and epistatic interactions for seed protein concentration in soybean under multiple environments based on a high-density map

“…QPor20-1 mapped with a smaller confidence interval at the central part of many published QTLs, which were also identified by Diers et al (1992), Sebolt et al (2000), Brummer et al (1997), Tajuddin et al (2003), Chung et al (2003), Nichols et al (2006), Lu et al (2013) and Pandurangan et al (2012) in the classic population. These QTLs were detected in at least one macro-environment that corresponded to the combination of year and location (Palomeque et al 2009), and align consistently with previous research.…”