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The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance.

Bao A, Zhao Z, Ding G, Shi L, Xu F, Cai H - Int J Mol Sci (2015)

Bottom Line: The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems.Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage.These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

View Article: PubMed Central - PubMed

Affiliation: Microelement Research Center, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China. baoaili19870212@163.com.

ABSTRACT
Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

No MeSH data available.


Related in: MedlinePlus

The 15N (15N%) and total nitrogen content (TN%) in the roots, stems and uppermost leaves of the GS2-cosuppressed plants (Co-sup-GS2) and wild-type plants (WT) at 1 h, 3 h, 8 h, 1 day and 3 days after NH4NO3 in the nutrient solution was replaced with 15NH415NO3 during the tillering stage. The values are the means from three biological replicated plant materials.
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ijms-16-12713-f002: The 15N (15N%) and total nitrogen content (TN%) in the roots, stems and uppermost leaves of the GS2-cosuppressed plants (Co-sup-GS2) and wild-type plants (WT) at 1 h, 3 h, 8 h, 1 day and 3 days after NH4NO3 in the nutrient solution was replaced with 15NH415NO3 during the tillering stage. The values are the means from three biological replicated plant materials.

Mentions: As GS is the main enzyme that assimilates NH4+ into Gln, we analyzed the nitrogen uptake and transport ability of the GS2-cosuppressed plants at the tillering stage using 15N. The total carbon and nitrogen concentration and the carbon/nitrogen ratio were also determined in the roots, stems and leaves of GS2-cosuppressed plants and wild-type plants under N, G and N + G growth conditions at the tillering stage. For the nitrogen uptake assay, the NH4NO3 in the nutrient solution was replaced by 15NH415NO3. After 1 h, 3 h, 8 h, 1 day and 3 days, the concentrations of total nitrogen and 15N in the roots, stems and leaves were analyzed in the GS2-cosuppressed plants and wild-type plants. The results showed that there was no difference in the total nitrogen concentration in the root between the GS2-cosuppressed plants and the wild-type plants. The stem total nitrogen concentration of the GS2-cosuppressed plants was 16.5%–61.9% higher than that of the wild-type plants; while the leaf total nitrogen concentration was 5.5%–16.6% lower than that of the wild-type plants (Figure 2). Similarly, there was no difference in the 15N concentration in the roots between the GS2-cosuppressed plants and the wild-type plants. The 15N concentration in the stems of the GS2-cosuppressed plants was 11.4%–66.7% higher than that of the wild-type plants; while 3 d after the NH4NO3 in the nutrient solution was replaced with 15NH415NO3, the 15N concentration in the leaves of the GS2-cosuppressed plants was 25.0% lower than in the wild-type plants (Figure 2). For the total carbon and nitrogen concentration analysis, significant (p < 0.01) increases in the total nitrogen concentration (26.0%, 32.7% and 18.1%) and significant (p < 0.05) decreases in the carbon/nitrogen ratio (20.2%, 24.0% and 17.9%) in the stem were observed in the GS2-cosuppressed plants grown under N, G and N + G conditions, respectively (Table 2). In addition, 3.8%, 5.3% and 9.9% decreases in the total nitrogen concentration were also observed in the GS2-cosuppressed plant leaves grown under the N, G and N + G conditions, respectively (Table 2). These results indicated a similar nitrogen uptake ability in roots between the GS2-cosuppressed plants and the wild-type plants, while a poor nitrogen transport ability from stems to leaves was observed, which led to nitrogen accumulation (especially the NO3−; data not shown here) and a decrease in the carbon/nitrogen ratio in the stems of the GS2-cosuppressed plants.


The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance.

Bao A, Zhao Z, Ding G, Shi L, Xu F, Cai H - Int J Mol Sci (2015)

The 15N (15N%) and total nitrogen content (TN%) in the roots, stems and uppermost leaves of the GS2-cosuppressed plants (Co-sup-GS2) and wild-type plants (WT) at 1 h, 3 h, 8 h, 1 day and 3 days after NH4NO3 in the nutrient solution was replaced with 15NH415NO3 during the tillering stage. The values are the means from three biological replicated plant materials.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490469&req=5

ijms-16-12713-f002: The 15N (15N%) and total nitrogen content (TN%) in the roots, stems and uppermost leaves of the GS2-cosuppressed plants (Co-sup-GS2) and wild-type plants (WT) at 1 h, 3 h, 8 h, 1 day and 3 days after NH4NO3 in the nutrient solution was replaced with 15NH415NO3 during the tillering stage. The values are the means from three biological replicated plant materials.
Mentions: As GS is the main enzyme that assimilates NH4+ into Gln, we analyzed the nitrogen uptake and transport ability of the GS2-cosuppressed plants at the tillering stage using 15N. The total carbon and nitrogen concentration and the carbon/nitrogen ratio were also determined in the roots, stems and leaves of GS2-cosuppressed plants and wild-type plants under N, G and N + G growth conditions at the tillering stage. For the nitrogen uptake assay, the NH4NO3 in the nutrient solution was replaced by 15NH415NO3. After 1 h, 3 h, 8 h, 1 day and 3 days, the concentrations of total nitrogen and 15N in the roots, stems and leaves were analyzed in the GS2-cosuppressed plants and wild-type plants. The results showed that there was no difference in the total nitrogen concentration in the root between the GS2-cosuppressed plants and the wild-type plants. The stem total nitrogen concentration of the GS2-cosuppressed plants was 16.5%–61.9% higher than that of the wild-type plants; while the leaf total nitrogen concentration was 5.5%–16.6% lower than that of the wild-type plants (Figure 2). Similarly, there was no difference in the 15N concentration in the roots between the GS2-cosuppressed plants and the wild-type plants. The 15N concentration in the stems of the GS2-cosuppressed plants was 11.4%–66.7% higher than that of the wild-type plants; while 3 d after the NH4NO3 in the nutrient solution was replaced with 15NH415NO3, the 15N concentration in the leaves of the GS2-cosuppressed plants was 25.0% lower than in the wild-type plants (Figure 2). For the total carbon and nitrogen concentration analysis, significant (p < 0.01) increases in the total nitrogen concentration (26.0%, 32.7% and 18.1%) and significant (p < 0.05) decreases in the carbon/nitrogen ratio (20.2%, 24.0% and 17.9%) in the stem were observed in the GS2-cosuppressed plants grown under N, G and N + G conditions, respectively (Table 2). In addition, 3.8%, 5.3% and 9.9% decreases in the total nitrogen concentration were also observed in the GS2-cosuppressed plant leaves grown under the N, G and N + G conditions, respectively (Table 2). These results indicated a similar nitrogen uptake ability in roots between the GS2-cosuppressed plants and the wild-type plants, while a poor nitrogen transport ability from stems to leaves was observed, which led to nitrogen accumulation (especially the NO3−; data not shown here) and a decrease in the carbon/nitrogen ratio in the stems of the GS2-cosuppressed plants.

Bottom Line: The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems.Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage.These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

View Article: PubMed Central - PubMed

Affiliation: Microelement Research Center, Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China. baoaili19870212@163.com.

ABSTRACT
Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

No MeSH data available.


Related in: MedlinePlus