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Iron deficiency affects nitrogen metabolism in cucumber (Cucumis sativus L.) plants.

Borlotti A, Vigani G, Zocchi G - BMC Plant Biol. (2012)

Bottom Line: Under Fe deficiency, only nitrate reductase (EC 1.7.1.1) activity decreased both at the root and leaf level, whilst for glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.1.14) an increase was found.Accordingly, the transcript analysis for these enzymes showed the same behaviour except for root nitrate reductase which increased.Furthermore, it was found that amino acid concentration greatly decreased in Fe-deficient roots, whilst it increased in the corresponding leaves.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia, Università degli Studi di Milano, Milano, Italy.

ABSTRACT

Background: Nitrogen is a principal limiting nutrient in plant growth and development. Among factors that may limit NO3- assimilation, Fe potentially plays a crucial role being a metal cofactor of enzymes of the reductive assimilatory pathway. Very few information is available about the changes of nitrogen metabolism occurring under Fe deficiency in Strategy I plants. The aim of this work was to study how cucumber (Cucumis sativus L.) plants modify their nitrogen metabolism when grown under iron deficiency.

Results: The activity of enzymes involved in the reductive assimilation of nitrate and the reactions that produce the substrates for the ammonium assimilation both at root and at leaf levels in Fe-deficient cucumber plants were investigated. Under Fe deficiency, only nitrate reductase (EC 1.7.1.1) activity decreased both at the root and leaf level, whilst for glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.1.14) an increase was found. Accordingly, the transcript analysis for these enzymes showed the same behaviour except for root nitrate reductase which increased. Furthermore, it was found that amino acid concentration greatly decreased in Fe-deficient roots, whilst it increased in the corresponding leaves. Moreover, amino acids increased in the xylem sap of Fe-deficient plants.

Conclusions: The data obtained in this work provided new insights on the responses of plants to Fe deficiency, suggesting that this nutritional disorder differentially affected N metabolism in root and in leaf. Indeed under Fe deficiency, roots respond more efficiently, sustaining the whole plant by furnishing metabolites (i.e. aa, organic acids) to the leaves.

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Enzymatic assay of ALT and AST. The assay was performed on root and leaf of plant during the progression of Fe deficiency treatment. Sampling was performed at 0, 1, 3, 7 days after Fe withdrawing. The meaning of the columns and the measurement units of enzymatic activities is as reported in Figure2. AST activity of control (0 d) was 17 and 30 nmol NADH mg-1 prot min-1 for root and leaf, respectively. ALT activity of control (0 d) was 29 and 20 nmol NADH mg-1 prot min-1 for root and leaf, respectively (complete activity data are reported in Additional file1). Data are means ± SE (n = 3). In the case of significant difference (P<0.05) values with different letters are statistically different.
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Figure 7: Enzymatic assay of ALT and AST. The assay was performed on root and leaf of plant during the progression of Fe deficiency treatment. Sampling was performed at 0, 1, 3, 7 days after Fe withdrawing. The meaning of the columns and the measurement units of enzymatic activities is as reported in Figure2. AST activity of control (0 d) was 17 and 30 nmol NADH mg-1 prot min-1 for root and leaf, respectively. ALT activity of control (0 d) was 29 and 20 nmol NADH mg-1 prot min-1 for root and leaf, respectively (complete activity data are reported in Additional file1). Data are means ± SE (n = 3). In the case of significant difference (P<0.05) values with different letters are statistically different.

Mentions: We have assayed the activity of two enzymes that are recognised to be involved in the recycling of aa i.e. the alanine-aminotransferase (ALT) and the aspartate-aminotransferase (AST). AST was also considered, along with ICDH, as one of the main candidates in the synthesis of 2-OG[35]. As shown in Figure7 (Additional file1), during the progression of Fe deficiency the activity of these two enzymes increased only in roots, while it did not significantly change in leaves.


Iron deficiency affects nitrogen metabolism in cucumber (Cucumis sativus L.) plants.

Borlotti A, Vigani G, Zocchi G - BMC Plant Biol. (2012)

Enzymatic assay of ALT and AST. The assay was performed on root and leaf of plant during the progression of Fe deficiency treatment. Sampling was performed at 0, 1, 3, 7 days after Fe withdrawing. The meaning of the columns and the measurement units of enzymatic activities is as reported in Figure2. AST activity of control (0 d) was 17 and 30 nmol NADH mg-1 prot min-1 for root and leaf, respectively. ALT activity of control (0 d) was 29 and 20 nmol NADH mg-1 prot min-1 for root and leaf, respectively (complete activity data are reported in Additional file1). Data are means ± SE (n = 3). In the case of significant difference (P<0.05) values with different letters are statistically different.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539955&req=5

Figure 7: Enzymatic assay of ALT and AST. The assay was performed on root and leaf of plant during the progression of Fe deficiency treatment. Sampling was performed at 0, 1, 3, 7 days after Fe withdrawing. The meaning of the columns and the measurement units of enzymatic activities is as reported in Figure2. AST activity of control (0 d) was 17 and 30 nmol NADH mg-1 prot min-1 for root and leaf, respectively. ALT activity of control (0 d) was 29 and 20 nmol NADH mg-1 prot min-1 for root and leaf, respectively (complete activity data are reported in Additional file1). Data are means ± SE (n = 3). In the case of significant difference (P<0.05) values with different letters are statistically different.
Mentions: We have assayed the activity of two enzymes that are recognised to be involved in the recycling of aa i.e. the alanine-aminotransferase (ALT) and the aspartate-aminotransferase (AST). AST was also considered, along with ICDH, as one of the main candidates in the synthesis of 2-OG[35]. As shown in Figure7 (Additional file1), during the progression of Fe deficiency the activity of these two enzymes increased only in roots, while it did not significantly change in leaves.

Bottom Line: Under Fe deficiency, only nitrate reductase (EC 1.7.1.1) activity decreased both at the root and leaf level, whilst for glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.1.14) an increase was found.Accordingly, the transcript analysis for these enzymes showed the same behaviour except for root nitrate reductase which increased.Furthermore, it was found that amino acid concentration greatly decreased in Fe-deficient roots, whilst it increased in the corresponding leaves.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Scienze Agrarie e Ambientali - Produzione, Territorio, Agroenergia, Università degli Studi di Milano, Milano, Italy.

ABSTRACT

Background: Nitrogen is a principal limiting nutrient in plant growth and development. Among factors that may limit NO3- assimilation, Fe potentially plays a crucial role being a metal cofactor of enzymes of the reductive assimilatory pathway. Very few information is available about the changes of nitrogen metabolism occurring under Fe deficiency in Strategy I plants. The aim of this work was to study how cucumber (Cucumis sativus L.) plants modify their nitrogen metabolism when grown under iron deficiency.

Results: The activity of enzymes involved in the reductive assimilation of nitrate and the reactions that produce the substrates for the ammonium assimilation both at root and at leaf levels in Fe-deficient cucumber plants were investigated. Under Fe deficiency, only nitrate reductase (EC 1.7.1.1) activity decreased both at the root and leaf level, whilst for glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.1.14) an increase was found. Accordingly, the transcript analysis for these enzymes showed the same behaviour except for root nitrate reductase which increased. Furthermore, it was found that amino acid concentration greatly decreased in Fe-deficient roots, whilst it increased in the corresponding leaves. Moreover, amino acids increased in the xylem sap of Fe-deficient plants.

Conclusions: The data obtained in this work provided new insights on the responses of plants to Fe deficiency, suggesting that this nutritional disorder differentially affected N metabolism in root and in leaf. Indeed under Fe deficiency, roots respond more efficiently, sustaining the whole plant by furnishing metabolites (i.e. aa, organic acids) to the leaves.

Show MeSH
Related in: MedlinePlus