Two cytosolic glutamine synthetase isoforms play specific roles for seed germination and seed yield structure in Arabidopsis

Guan, Miao; Møller, Inge Skrumsager; Schjøerring, Jan K.

doi:10.1093/jxb/eru411

Cited by 77 publications

(94 citation statements)

References 51 publications

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“…Gln, the main amino acid remobilized in Arabidopsis during the reproductive phase (Figs. 4B and 6B; Guiboileau et al, 2012;Guan et al, 2015), has been discussed as a regulatory feedback signal, and the accumulation of the amide in aap8 leaves agrees with this assumption (Fig. 4B; Fan et al, 2006).…”

Section: Aap8 Function Affects Leaf N Metabolism During Reproductive supporting

confidence: 73%

“…8, A-D). Similar effects on sink development were observed for an Arabidopsis mutant of a Gln synthetase important for leaf N remobilization and export (Guan et al, 2015). The reduction in fruit number in aap8 plants supports that decreased amino acid remobilization and phloem loading causes N limitation conditions early in reproductive development.…”

Section: Aap8 Function In Phloem Loading Of Amino Acids Is Essential supporting

confidence: 67%

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Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids

2016

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Allocation of large amounts of nitrogen to developing organs occurs in the phloem and is essential for plant growth and seed development. In Arabidopsis (Arabidopsis thaliana) and many other plant species, amino acids represent the dominant nitrogen transport forms in the phloem, and they are mainly synthesized in photosynthetically active source leaves. Following their synthesis, a broad spectrum of the amino nitrogen is actively loaded into the phloem of leaf minor veins and transported within the phloem sap to sinks such as developing leaves, fruits, or seeds. Controlled regulation of the source-to-sink transport of amino acids has long been postulated; however, the molecular mechanism of amino acid phloem loading was still unknown. In this study, Arabidopsis AMINO ACID PERMEASE8 (AAP8) was shown to be expressed in the source leaf phloem and localized to the plasma membrane, suggesting its function in phloem loading. This was further supported by transport studies with aap8 mutants fed with radiolabeled amino acids and by leaf exudate analyses. In addition, biochemical and molecular analyses revealed alterations in leaf nitrogen pools and metabolism dependent on the developmental stage of the mutants. Decreased amino acid phloem loading and partitioning to sinks led to decreased silique and seed numbers, but seed protein levels were unchanged, demonstrating the importance of AAP8 function for sink development rather than seed quality. Overall, these results show that AAP8 plays an important role in source-to-sink partitioning of nitrogen and that its function affects source leaf physiology and seed yield.

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Section: Aap8 Function Affects Leaf N Metabolism During Reproductive supporting

confidence: 73%

Section: Aap8 Function In Phloem Loading Of Amino Acids Is Essential supporting

confidence: 67%

Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids

2016

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“…3, B and D). This contrasts with Arabidopsis, which produces fewer seeds but with sufficient N/storage protein when N phloem loading, and subsequently, delivery to seeds is reduced (Schmidt et al, 2007;Bennett et al, 2012;Guan et al, 2015;Santiago and Tegeder, 2016). These variations in seed number or seed protein levels under N stress may point to species-specific survival strategies (Fageria and Baligar, 2005;Hirel et al, 2007).…”

Section: Nue Is Greatly Improved In Aap1-oe Plantsmentioning

confidence: 99%

Improving Plant Nitrogen Use Efficiency through Alteration of Amino Acid Transport Processes

2017

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Improving the efficiency of nitrogen (N) uptake and utilization in plants could potentially increase crop yields while reducing N fertilization and, subsequently, environmental pollution. Within most plants, N is transported primarily as amino acids. In this study, pea (Pisum sativum) plants overexpressing AMINO ACID PERMEASE1 (AAP1) were used to determine if and how genetic manipulation of amino acid transport from source to sink affects plant N use efficiency. The modified plants were grown under low, moderate, or high N fertilization regimes. The results showed that, independent of the N nutrition, the engineered plants allocate more N via the vasculature to the shoot and seeds and produce more biomass and higher seed yields than wild-type plants. Dependent on the amount of N supplied, the AAP1-overexpressing plants displayed improved N uptake or utilization efficiency, or a combination of the two. They also showed significantly increased N use efficiency in N-deficient as well as in N-rich soils and, impressively, required half the amount of N to produce as many fruits and seeds as control plants. Together, these data support that engineering N allocation from source to sink presents an effective strategy to produce crop plants with improved productivity as well as N use efficiency in a range of N environments.Nitrogen (N) is an essential nutrient that plants require in large amounts for growth and development. In industrial countries, high N fertilization enables maximum crop yields, and in the last 50 years, the use of synthetic N fertilizers has increased dramatically to meet the agricultural demands of a growing population (FAO, 2012;Conant et al., 2013). However, depending on the crop species and soil conditions, plants take up less than half of the applied N fertilizer (Raun and Johnson, 1999;Hodge et al., 2000;Kumar and Goh, 2002;Yang et al., 2015;Zhu et al., 2016). The remaining soil N may contaminate aquatic systems through runoffs or leached water (Crews and Peoples, 2005;Gruber and Galloway, 2008) or it may undergo denitrification and be released into the atmosphere as nitrous oxide, a powerful greenhouse gas (Bouwman, 1996;Bouwman et al., 2002), altogether resulting in negative effects on the environment and human health. Oppositely, in developing countries, access to N fertilizer is limited, and insufficient N nutrition results in low crop productivity and, ultimately, in reduced food supply (Brown et al., 2009;Lal, 2009).One solution to these issues is the production of crop varieties that are highly efficient in using N and produce high yields with reduced N input (MasclauxDaubresse et al., 2010;McAllister et al., 2012;Garnett et al., 2015). Plant nitrogen use efficiency (NUE) is determined by plant seed yield relative to the amount of N applied and is generally composed of both N uptake and N utilization efficiency (Moll et al., 1982). Nitrogen uptake efficiency (NUpE) is defined as total shoot N relative to the amount of N supplied to the soil. The uptake of N by the root is influenced by th...

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“…1 Arabidopsis has 5 isogenes for GS1 (Gln1;1-5) and among these Gln1;2 seems to play particular roles for ammonium assimilation in roots as well as for nitrogen remobilization during seed germination and seed production. 2 However, the separate importance of the root and shoot functions of Gln1;2 and their mutual interdependence are not known.…”

Section: Introductionmentioning

confidence: 99%

Peering into the separate roles of root and shoot cytosolic glutamine synthetase 1;2 by use of grafting experiments in Arabidopsis

Guan

Schjøerring

2016

Plant Signaling & Behavior

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Cytosolic glutamine synthetase 1;2 plays an important role in the primary nitrogen assimilation in roots. Based on characterization of the knockout mutant gln1;2 we have recently demonstrated that Gln1;2 is also essential for ammonium handling in shoots. Here we built reciprocally grafted plants between wild type (Wt) and gln1;2 in order to separate the root and shoot roles of Gln1;2. Significant reduction in silique number and seed yield were observed in the grafted plants 1;2 shoot /Wt root relative to Wt shoot /1;2 root and Wt shoot / Wt root . Shoot Gln1;2 thus played a crucial role for seed production. Tracing experiments with 15 N showed that the relative nitrogen remobilization from vegetative organs to seeds in gln1;2 was just as efficient as in the Wt plants. This was the case although the total quantity of nitrogen in gln1;2 was significantly lower compared to that in the Wt. We conclude that the functions of shoot Gln1;2 are primarily associated with internal N signaling for establishment of seed yield capacity rather than with nitrogen remobilization.

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Two cytosolic glutamine synthetase isoforms play specific roles for seed germination and seed yield structure in Arabidopsis

Abstract: SummaryKnockout of glutamine synthetase isogene Gln1;2 reduces nitrogen remobilization and the number and size of siliques and seeds in Arabidopsis. Gln1;1 affects the response of primary root development to exogenous nitrogen.

Cited by 77 publications

References 51 publications

Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids

Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids

Improving Plant Nitrogen Use Efficiency through Alteration of Amino Acid Transport Processes

Peering into the separate roles of root and shoot cytosolic glutamine synthetase 1;2 by use of grafting experiments in Arabidopsis

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