Glutamate synthase activities and protein changes in relation to nitrogen nutrition in barley: the dependence on different plastidic glucose-6P dehydrogenase isoforms

Esposito, Sergio; Guerriero, Gea; Vona, Vincenza; Rigano, Vittoria Di Martino; Carfagna, Simona; Rigano, Carmelo

doi:10.1093/jxb/eri006

Cited by 39 publications

(53 citation statements)

References 45 publications

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“…The efficiency of NH 4 + assimilation could contribute to the overall plant NUE (Foulkes et al, 2009). The assimilation of NH 4 + into amino acids occurs via action of glutamine synthetase (GS) and glutamate synthase (GOGAT) enzymes (Esposito et al, 2005). Glutamate dehydrogenase (GDH) constitute an alternative pathway of NH 4 + assimilation (Hirel et al, 2007;Shrawat and Good, 2008).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen Nutrition, its Assimilation and Remobilization in Diverse Wheat Genotypes

Kaur¹,

Asthir²,

Bains³

et al. 2015

IJAB

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Nitrogen is an essential element required for plant growth and development. However, over-use of nitrogen fertilizer is not only costly but also environmentally unsafe. Therefore, identification of genotypes possessing higher nitrogen use efficiency (NUE) at sub-optimal dose of nitrogen is the key challenge. In this study, effect of nitrogen on the activities of nitrogen assimilatory enzymes, total soluble proteins and amino acids was studied in wheat genotypes of diverse physiology (viz., GLU 1101, GLU 1356, GLU 2001. Nitrogen was applied at recommended dose (RDN), RDN-50%, RDN-25% and RDN+25% using urea as a source. With increase of nitrogen rate, significant increase in the activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase was noted, which caused an increase in protein and amino acid contents in all the genotypes. Activity pattern of studied enzymes revealed an increasing trend from tillering to anthesis stage and thereafter declined in parallel with decrease in protein and amino acid contents. Conversely, nitrogen and chlorophyll content showed a consistent decline with leaf growth. Genotypes GLU 1356 and GLU 2001 maintained higher activities of nitrogen assimilatory enzymes in parallel with higher NUE at RDN-50% and RDN-25%, while genotypes PH132-4836 and PH132-4840 were found to be promising at RDN+25%. A positive correlation of nitrogen assimilatory enzymes (nitrate reductase and glutamine synthetase) with NUE and nitrogen content was also observed indicating that these might be the rate limiting enzymes in nitrogen metabolism. In crux, 25% less than the recommended dose of nitrogen had significant influence on nitrogen metabolism especially in GLU 1356 and GLU 2001 due to high activities of nitrate reductase and glutamine synthetase. These nitrogen efficient genotypes may be exploited in enhancing wheat crop productivity under lower dose of nitrogen to save environment and input cost.

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Section: Introductionmentioning

confidence: 99%

Nitrogen Nutrition, its Assimilation and Remobilization in Diverse Wheat Genotypes

Kaur¹,

Asthir²,

Bains³

et al. 2015

IJAB

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“…There was however, a significant effect of nitrate concentration in the root zone (Table 7), with the expression of the three GOGAT genes higher in both the high N treatments than in the low N treatment (Table 8A). This result is consistent with increased GOGAT enzyme activity with increased N assimilation (Esposito et al, 2005). Nitrate starvation for 3 days reduced the expression of the three genes (Table 8A), indicating a decrease in N assimilation within a short period of time.…”

Section: Gogat Gene Expressionsupporting

confidence: 83%

Genome wide analysis and allele mining of diverse sorghum genes involved in nitrogen use efficiency

Diatloff¹

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Nitrogen (N) is the most important plant nutrient and is the most commonly applied element to agricultural crops. In many cases nitrogen fertiliser is the main input cost for farmers, and in addition, is a major pollutant from agricultural activity. Most plants only take up 50% or less of the applied N, and most of the remainder is lost to leaching into ground water and waterways, or volatilised into the atmosphere. Hence, improving the nitrogen responsiveness of crops is crucial for food security and environmental sustainability, and breeding N use efficient (NUE) crops has to exploit genetic variation for this complex trait.In this thesis, reverse genetics was used to examine allelic variation in two key N metabolism genes. In silico analysis of the genomes of 44 genetically diverse sorghum genotypes identified a nitrate reductase and a glutamate synthase gene (NADH-GOGAT) that were under balancing selection in improved sorghum cultivars. It was hypothesised that these genes are a potential source of differences in NUE, and parents and progenies of nested association mapping populations were selected with different allelic combinations for these genes. Allelic variation was sourced from African (Macia) and Indian (ICSV754) genotypes that had been backcrossed into the Australian elite parent R931945-2-2. Nine genotypes with different allelic combinations were grown for 30 days in a glasshouse and supplied with continuous limiting (1 mM nitrate) or replete N (10 mM nitrate), or replete N for 27 days followed by three days N starvation prior to harvest. Biomass, N and nitrate contents were quantified together with gene expressions in leaves, stems and roots.Limiting N supply universally resulted in less shoot and root growth, increased root weight ratio, reduced tissue nitrate and N concentrations, and reduced NADH-GOGAT expression. None of the tested genotypes exceeded growth or NUE of elite parent R931945-2-2. This may indicate that the allelic combinations did not confer an advantage during early vegetative growth, or that selection in a modern plant breeding program has already optimised the allelic combinations for these loci. It is also noteworthy that plants were grown under controlled environment conditions, and field responses may have been somewhat different. It is also possible that any selective advantage of other allelic combinations may only have been apparent in plants grown to anthesis and/or grain maturity. Thus, the next steps for ascertaining potential effects on NUE include growing plants to maturity. It is concluded that reverse genetics that take advantage of rapidly expanding genomic databases contributes towards a systematic approach for developing N efficient crops.ii

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“…Crude extracts or purified G6PDHs were processed by SDS-PAGE performed in 10% gels (4% stacking gel) loaded with crude extracts or purified proteins, and run as previously described for 120 min at 180 V/30 mA (Esposito et al 2005). Gels were stained with coomassie blue or silver stain (Sigma Prot-Sil 1) techniques.…”

Section: Sds-page and Western Blottingmentioning

confidence: 99%

“…The separated polypeptides were transferred to a 0.2 lm nitrocellulose membrane (Hoefer Mini Blot Module), then incubated for 2 h at room temperature with G6PDH antibodies raised against the potato cytosolic, chloroplastic P1-G6PDH or plastidic P2-G6PDH as described by Wendt et al (2000). After incubating the membrane with secondary antibodies, cross reacting polypeptides were identified and stained for alkaline phosphatase activity (Esposito et al 2005).…”

Section: Sds-page and Western Blottingmentioning

confidence: 99%

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Glucose-6P dehydrogenase in Chlorella sorokiniana (211/8k): an enzyme with unusual characteristics

Esposito

Guerriero

Vona

et al. 2005

Planta

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In Chlorella sorokiniana (211/8k), glucose-6 phosphate dehydrogenase (G6PDH-EC 1.1.1.49) activity is similar in both N-starved cells and nitrate-grown algae when expressed on a PCV basis. A single G6PDH isoform was purified from Chlorella cells grown under different nutrient conditions; the presence of a single G6PDH was confirmed by native gels stained for enzyme activity and by Western blots. The algal G6PDH is recognised only by antibodies raised against higher plants plastidic protein, but not by chloroplastic and cytosolic isoform-specific antisera. Purified G6PDH showed kinetic parameters similar to plastidic isoforms of higher plants, suggesting a different biochemical structure which would confer peculiar regulative properties to the algal G6PDH with respect to higher plants enzymes. The most remarkable property of algal G6PDH is represented by the response to NADPH inhibition. The algal enzyme is less sensitive to NADPH effects compared to higher plants G6PDH: Ki(NADPH) is 103 microM for G6PDH from nitrogen-starved C. sorokiniana, similarly to root plastidic P2-G6PDH. In nitrate-grown C. sorokiniana the Ki(NADPH) decreased to 48 microM, whereas other kinetic parameters remained unchanged. These results will allow further investigations in order to rule out possible modifications of the enzyme, and/or the expression of a different G6PDH isoform during nitrate assimilation.

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Glutamate synthase activities and protein changes in relation to nitrogen nutrition in barley: the dependence on different plastidic glucose-6P dehydrogenase isoforms

Cited by 39 publications

References 45 publications

Nitrogen Nutrition, its Assimilation and Remobilization in Diverse Wheat Genotypes

Nitrogen Nutrition, its Assimilation and Remobilization in Diverse Wheat Genotypes

Genome wide analysis and allele mining of diverse sorghum genes involved in nitrogen use efficiency

Glucose-6P dehydrogenase in Chlorella sorokiniana (211/8k): an enzyme with unusual characteristics

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