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Additional nitrogen fertilization at heading time of rice down-regulates cellulose synthesis in seed endosperm.

Midorikawa K, Kuroda M, Terauchi K, Hoshi M, Ikenaga S, Ishimaru Y, Abe K, Asakura T - PLoS ONE (2014)

Bottom Line: As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed.Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression.These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

ABSTRACT
The balance between carbon and nitrogen is a key determinant of seed storage components, and thus, is of great importance to rice and other seed-based food crops. To clarify the influence of the rhizosphere carbon/nitrogen balance during the maturation stage of several seed components, transcriptome analysis was performed on the seeds from rice plants that were provided additional nitrogen fertilization at heading time. As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed. Moreover, cellulose and sucrose synthases, which are involved in cellulose synthesis, were down-regulated. Therefore, we compared cellulose content of mature seeds that were treated with additional nitrogen fertilization with those from control plants using calcofluor staining. In these experiments, cellulose content in endosperm from plants receiving additional nitrogen fertilization was less than that in control endosperm. Other starch synthesis-related genes such as starch synthase 1, starch phosphorylase 2, and branching enzyme 3 were also down-regulated, whereas some α-amylase and β-amylase genes were up-regulated. On the other hand, mRNA expression of amino acid biosynthesis-related molecules was up-regulated. Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression. These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.

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Amino acid and protein contents of mature polished rice cultivated in a field.Field trials were conducted for three years and data are expressed as means of the three trials. Filled bars correspond with samples from the N-fertilized plot and unfilled bars correspond with samples from the control plot. Error bars represent standard deviation (SD; *P<0.01) (A) Total amino acid content was analyzed after hydrolysis using hydrogen chloride. (B) Protein content was estimated using the Kjeldahl method.
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pone-0098738-g002: Amino acid and protein contents of mature polished rice cultivated in a field.Field trials were conducted for three years and data are expressed as means of the three trials. Filled bars correspond with samples from the N-fertilized plot and unfilled bars correspond with samples from the control plot. Error bars represent standard deviation (SD; *P<0.01) (A) Total amino acid content was analyzed after hydrolysis using hydrogen chloride. (B) Protein content was estimated using the Kjeldahl method.

Mentions: In general, enriched nitrogen fertilization elevates protein content, as determined using the Kjeldahl method [10]. In agreement, the sum of amino acid and protein content, were elevated in mature rice treated with additional fertilization in all trials (Fig. 2 and Table S1). As shown in Table S1, amino acid content was also higher in individuals from the N-fertilized plot in all trials. However, free amino acid levels remained low or undetectable in all trials (Table S1). These results indicate that nitrogen fertilization at heading time was mainly utilized for protein synthesis and not for the accumulation of free amino acids. At the third field trial, we took some preliminary results about developing grains. Grain weight did not differ significantly between plants from the N-fertilized and control plot at every sampling time (data not shown). Although differences were not statistically confirmed, seed nitrogen content was higher in the N-fertilized plot than that in the control plot at every sampling time. It is a reasonable speculation that gene expression in developing grain also changes in response to additional nitrogen fertilization.


Additional nitrogen fertilization at heading time of rice down-regulates cellulose synthesis in seed endosperm.

Midorikawa K, Kuroda M, Terauchi K, Hoshi M, Ikenaga S, Ishimaru Y, Abe K, Asakura T - PLoS ONE (2014)

Amino acid and protein contents of mature polished rice cultivated in a field.Field trials were conducted for three years and data are expressed as means of the three trials. Filled bars correspond with samples from the N-fertilized plot and unfilled bars correspond with samples from the control plot. Error bars represent standard deviation (SD; *P<0.01) (A) Total amino acid content was analyzed after hydrolysis using hydrogen chloride. (B) Protein content was estimated using the Kjeldahl method.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4048278&req=5

pone-0098738-g002: Amino acid and protein contents of mature polished rice cultivated in a field.Field trials were conducted for three years and data are expressed as means of the three trials. Filled bars correspond with samples from the N-fertilized plot and unfilled bars correspond with samples from the control plot. Error bars represent standard deviation (SD; *P<0.01) (A) Total amino acid content was analyzed after hydrolysis using hydrogen chloride. (B) Protein content was estimated using the Kjeldahl method.
Mentions: In general, enriched nitrogen fertilization elevates protein content, as determined using the Kjeldahl method [10]. In agreement, the sum of amino acid and protein content, were elevated in mature rice treated with additional fertilization in all trials (Fig. 2 and Table S1). As shown in Table S1, amino acid content was also higher in individuals from the N-fertilized plot in all trials. However, free amino acid levels remained low or undetectable in all trials (Table S1). These results indicate that nitrogen fertilization at heading time was mainly utilized for protein synthesis and not for the accumulation of free amino acids. At the third field trial, we took some preliminary results about developing grains. Grain weight did not differ significantly between plants from the N-fertilized and control plot at every sampling time (data not shown). Although differences were not statistically confirmed, seed nitrogen content was higher in the N-fertilized plot than that in the control plot at every sampling time. It is a reasonable speculation that gene expression in developing grain also changes in response to additional nitrogen fertilization.

Bottom Line: As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed.Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression.These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

ABSTRACT
The balance between carbon and nitrogen is a key determinant of seed storage components, and thus, is of great importance to rice and other seed-based food crops. To clarify the influence of the rhizosphere carbon/nitrogen balance during the maturation stage of several seed components, transcriptome analysis was performed on the seeds from rice plants that were provided additional nitrogen fertilization at heading time. As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed. Moreover, cellulose and sucrose synthases, which are involved in cellulose synthesis, were down-regulated. Therefore, we compared cellulose content of mature seeds that were treated with additional nitrogen fertilization with those from control plants using calcofluor staining. In these experiments, cellulose content in endosperm from plants receiving additional nitrogen fertilization was less than that in control endosperm. Other starch synthesis-related genes such as starch synthase 1, starch phosphorylase 2, and branching enzyme 3 were also down-regulated, whereas some α-amylase and β-amylase genes were up-regulated. On the other hand, mRNA expression of amino acid biosynthesis-related molecules was up-regulated. Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression. These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.

Show MeSH