Limits...
Co-ordinated expression of amino acid metabolism in response to N and S deficiency during wheat grain filling.

Howarth JR, Parmar S, Jones J, Shepherd CE, Corol DI, Galster AM, Hawkins ND, Miller SJ, Baker JM, Verrier PJ, Ward JL, Beale MH, Barraclough PB, Hawkesford MJ - J. Exp. Bot. (2008)

Bottom Line: Canopy tissue N was remobilized effectively to the grain after anthesis.Nuclear magnetic resonance (NMR) metabolite profiling revealed significant effects of suboptimal N or S supply in leaves but not in developing grain.Grain N and S contents increased in parallel after anthesis and were not significantly affected by S deficiency, despite a suboptimal N:S ratio at final harvest.

View Article: PubMed Central - PubMed

Affiliation: Plant Sciences Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.

ABSTRACT
Increasing demands for productivity together with environmental concerns about fertilizer use dictate that the future sustainability of agricultural systems will depend on improving fertilizer use efficiency. Characterization of the biological processes responsible for efficient fertilizer use will provide tools for crop improvement under reduced inputs. Transcriptomic and metabolomic approaches were used to study the impact of nitrogen (N) and sulphur (S) deficiency on N and S remobilization from senescing canopy tissues during grain filling in winter wheat (Triticum aestivum). Canopy tissue N was remobilized effectively to the grain after anthesis. S was less readily remobilized. Nuclear magnetic resonance (NMR) metabolite profiling revealed significant effects of suboptimal N or S supply in leaves but not in developing grain. Analysis of amino acid pools in the grain and leaves revealed a strategy whereby amino acid biosynthesis switches to the production of glutamine during grain filling. Glutamine accumulated in the first 7 d of grain development, prior to conversion to other amino acids and protein in the subsequent 21 d. Transcriptome analysis indicated that a down-regulation of the terminal steps in many amino acid biosynthetic pathways occurs to control pools of amino acids during leaf senescence. Grain N and S contents increased in parallel after anthesis and were not significantly affected by S deficiency, despite a suboptimal N:S ratio at final harvest. N deficiency resulted in much slower accumulation of grain N and S and lower final concentrations, indicating that vegetative tissue N has a greater control of the timing and extent of nutrient remobilization than S.

Show MeSH
Post anthesis measurements of (A) chlorophyll (SPAD), (B) nitrogen, and (C) sulphur content of winter wheat (T. aestivum var Hereward) tissues during grain filling. Stems (filled squares) and leaves 1 (filled triangles), 2 (filled circles), and 3 (filled diamonds) (numbered from the flag leaf down) were harvested from control (N2), N-deficient (N1), and S-deficient (–S) plots. Contents were measured per plant part. Least significant difference (LSD) error bars were calculated from three biological replicates using a two-way ANOVA to test for significance at the 5% (P <0.05) level. SPAD readings were mean measurements from the leaves of 10 replicate main stems.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2561146&req=5

fig1: Post anthesis measurements of (A) chlorophyll (SPAD), (B) nitrogen, and (C) sulphur content of winter wheat (T. aestivum var Hereward) tissues during grain filling. Stems (filled squares) and leaves 1 (filled triangles), 2 (filled circles), and 3 (filled diamonds) (numbered from the flag leaf down) were harvested from control (N2), N-deficient (N1), and S-deficient (–S) plots. Contents were measured per plant part. Least significant difference (LSD) error bars were calculated from three biological replicates using a two-way ANOVA to test for significance at the 5% (P <0.05) level. SPAD readings were mean measurements from the leaves of 10 replicate main stems.

Mentions: Following anthesis, cell expansion and nuclear division establishes the cellular structure of the wheat grain that will eventually reach maturity. Subsequently the grain endosperm accumulates starch, oil, and protein, reaching its maximum fresh weight by ∼21 dpa. Between 21 and 30 dpa, the pericarp fuses with the maternal epidermis, the endosperm fills with starch and protein, and the embryo fully develops by ∼30 dpa (Wilson et al., 2004). In order to assess the rate of nutrient remobilization from vegetative tissues to grain during this period and to study the effect of fertilizer application on senescence processes, total N and S contents of individual plant parts and leaf chlorophyll measurements [using a SPAD (soil-plant analyses development) meter] were determined. Leaves 1 (flag) to 3 and whole main stems were harvested weekly from anthesis to 49 dpa from control (N2; 192 kg N ha−1), N-deficient (N1; 48 kg N ha−1), and S-deficient (–S; same N application as N2 but with no S) field plots (Fig. 1).


Co-ordinated expression of amino acid metabolism in response to N and S deficiency during wheat grain filling.

Howarth JR, Parmar S, Jones J, Shepherd CE, Corol DI, Galster AM, Hawkins ND, Miller SJ, Baker JM, Verrier PJ, Ward JL, Beale MH, Barraclough PB, Hawkesford MJ - J. Exp. Bot. (2008)

Post anthesis measurements of (A) chlorophyll (SPAD), (B) nitrogen, and (C) sulphur content of winter wheat (T. aestivum var Hereward) tissues during grain filling. Stems (filled squares) and leaves 1 (filled triangles), 2 (filled circles), and 3 (filled diamonds) (numbered from the flag leaf down) were harvested from control (N2), N-deficient (N1), and S-deficient (–S) plots. Contents were measured per plant part. Least significant difference (LSD) error bars were calculated from three biological replicates using a two-way ANOVA to test for significance at the 5% (P <0.05) level. SPAD readings were mean measurements from the leaves of 10 replicate main stems.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2561146&req=5

fig1: Post anthesis measurements of (A) chlorophyll (SPAD), (B) nitrogen, and (C) sulphur content of winter wheat (T. aestivum var Hereward) tissues during grain filling. Stems (filled squares) and leaves 1 (filled triangles), 2 (filled circles), and 3 (filled diamonds) (numbered from the flag leaf down) were harvested from control (N2), N-deficient (N1), and S-deficient (–S) plots. Contents were measured per plant part. Least significant difference (LSD) error bars were calculated from three biological replicates using a two-way ANOVA to test for significance at the 5% (P <0.05) level. SPAD readings were mean measurements from the leaves of 10 replicate main stems.
Mentions: Following anthesis, cell expansion and nuclear division establishes the cellular structure of the wheat grain that will eventually reach maturity. Subsequently the grain endosperm accumulates starch, oil, and protein, reaching its maximum fresh weight by ∼21 dpa. Between 21 and 30 dpa, the pericarp fuses with the maternal epidermis, the endosperm fills with starch and protein, and the embryo fully develops by ∼30 dpa (Wilson et al., 2004). In order to assess the rate of nutrient remobilization from vegetative tissues to grain during this period and to study the effect of fertilizer application on senescence processes, total N and S contents of individual plant parts and leaf chlorophyll measurements [using a SPAD (soil-plant analyses development) meter] were determined. Leaves 1 (flag) to 3 and whole main stems were harvested weekly from anthesis to 49 dpa from control (N2; 192 kg N ha−1), N-deficient (N1; 48 kg N ha−1), and S-deficient (–S; same N application as N2 but with no S) field plots (Fig. 1).

Bottom Line: Canopy tissue N was remobilized effectively to the grain after anthesis.Nuclear magnetic resonance (NMR) metabolite profiling revealed significant effects of suboptimal N or S supply in leaves but not in developing grain.Grain N and S contents increased in parallel after anthesis and were not significantly affected by S deficiency, despite a suboptimal N:S ratio at final harvest.

View Article: PubMed Central - PubMed

Affiliation: Plant Sciences Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.

ABSTRACT
Increasing demands for productivity together with environmental concerns about fertilizer use dictate that the future sustainability of agricultural systems will depend on improving fertilizer use efficiency. Characterization of the biological processes responsible for efficient fertilizer use will provide tools for crop improvement under reduced inputs. Transcriptomic and metabolomic approaches were used to study the impact of nitrogen (N) and sulphur (S) deficiency on N and S remobilization from senescing canopy tissues during grain filling in winter wheat (Triticum aestivum). Canopy tissue N was remobilized effectively to the grain after anthesis. S was less readily remobilized. Nuclear magnetic resonance (NMR) metabolite profiling revealed significant effects of suboptimal N or S supply in leaves but not in developing grain. Analysis of amino acid pools in the grain and leaves revealed a strategy whereby amino acid biosynthesis switches to the production of glutamine during grain filling. Glutamine accumulated in the first 7 d of grain development, prior to conversion to other amino acids and protein in the subsequent 21 d. Transcriptome analysis indicated that a down-regulation of the terminal steps in many amino acid biosynthetic pathways occurs to control pools of amino acids during leaf senescence. Grain N and S contents increased in parallel after anthesis and were not significantly affected by S deficiency, despite a suboptimal N:S ratio at final harvest. N deficiency resulted in much slower accumulation of grain N and S and lower final concentrations, indicating that vegetative tissue N has a greater control of the timing and extent of nutrient remobilization than S.

Show MeSH