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Identification and characterization of Arabidopsis AtNUDX9 as a GDP-d-mannose pyrophosphohydrolase: its involvement in root growth inhibition in response to ammonium.

Tanaka H, Maruta T, Ogawa T, Tanabe N, Tamoi M, Yoshimura K, Shigeoka S - J. Exp. Bot. (2015)

Bottom Line: The GDP-d-Man pyrophosphohydrolase activity was increased in the root of plants grown in the presence of ammonium.No difference was observed in the levels of AsA in the leaf and root tissues of the wild-type and knockout-nudx9 (KO-nudx9) plants, whereas a marked increase in N-glycoprotein levels and enhanced growth were detected in the roots of KO-nudx9 plants in the presence of ammonium.These results suggest that AtNUDX9 is involved in the regulation of GDP-d-Man levels affecting ammonium sensitivity via modulation of protein N-glycosylation in the roots.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.

No MeSH data available.


Ammonium sensitivity of AtNUDX9-disrupted or -suppressed Arabidopsis plants. Experimental conditions are the same as in Fig. 5. (A, B) Primary root length and relative root elongation, respectively, of the wild-type, KO-nudx9, KD-nudx9, and vtc1-1 plants grown on +NH4+and –NH4+mediums. In the data of relative root elongation, 100% corresponds to a primary root length of respective plants grown on –NH4+medium for 10 d. (C, D) Phenotypes. Scale bars, 1 and 0.5cm, respectively. The numbers (1 to 4) indicate the position of leaves. (E, F, G) Dry weight of leaves and roots, leaf area, and numbers of lateral roots of 10-d-old plants. The positions of leaves are described as in (D). Data represent means ±SD of 9–15 replicates. Values without a common letter were significantly different according to ANOVA (P <0.05). (This figure is available in colour at JXB online.)
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Figure 6: Ammonium sensitivity of AtNUDX9-disrupted or -suppressed Arabidopsis plants. Experimental conditions are the same as in Fig. 5. (A, B) Primary root length and relative root elongation, respectively, of the wild-type, KO-nudx9, KD-nudx9, and vtc1-1 plants grown on +NH4+and –NH4+mediums. In the data of relative root elongation, 100% corresponds to a primary root length of respective plants grown on –NH4+medium for 10 d. (C, D) Phenotypes. Scale bars, 1 and 0.5cm, respectively. The numbers (1 to 4) indicate the position of leaves. (E, F, G) Dry weight of leaves and roots, leaf area, and numbers of lateral roots of 10-d-old plants. The positions of leaves are described as in (D). Data represent means ±SD of 9–15 replicates. Values without a common letter were significantly different according to ANOVA (P <0.05). (This figure is available in colour at JXB online.)

Mentions: In order to determine whether AtNUDX9 was involved in NH4+sensitivity, the growth of wild-type, KO-nudx9, and KD-nudx9 plants were compared as well as the vtc1-1 mutants on the –NH4+and +NH4+media. Consistent with previous findings, root growth in the vtc1-1 mutants was inhibited more than that by the wild-type plants on the +NH4+medium (Qin et al., 2008; Barth et al., 2010) (Fig. 6A–C). No significant difference was noted in primary root length between the wild-type plants and vtc1-1 mutants on the –NH4+medium. An inverse correlation was observed between AtNUDX9 and VTC1 with regard to the effects of NH4+on root growth. The primary root lengths of the KO-nudx9 and KD-nudx9 plants were longer than those of the wild-type plants on the +NH4+medium, but not on the –NH4+medium (Fig. 6A, C). The relative primary root elongation of KO-nudx9 and KD-nudx9 was sustained even under the +NH4+medium (Fig. 6B). Furthermore, the dry weight of roots and numbers of lateral roots of the KO-nudx9 and KD-nudx9 plants on the +NH4+medium were increased compared with those of the wild-type plants (Fig. 6E, G). These results indicated that AtNUDX9 negatively modulated root growth in response to NH4+, possibly through the hydrolysis of GDP-d-Man. The aerial parts of all the genotypes tested here showed similar phenotypes on the –NH4+medium (Fig. 6C, D). On the other hand, the aerial parts of KO-nudx9 and KD-nudx9 plants were larger than the wild-type and vtc1-1 plants on the +NH4+medium. In fact, the leaf size and dry weight of aerial parts of KO-nudx9 and KD-nudx9 plants on the +NH4+medium were significantly increased compared with those of the wild-type plants (Fig. 6E, F). Considering the high expression levels of AtNUDX9 in root tissues, it is likely that the enhanced root growth in the KO-nudx9 and KD-nudx9 plants causes facilitation of the growth of aerial parts.


Identification and characterization of Arabidopsis AtNUDX9 as a GDP-d-mannose pyrophosphohydrolase: its involvement in root growth inhibition in response to ammonium.

Tanaka H, Maruta T, Ogawa T, Tanabe N, Tamoi M, Yoshimura K, Shigeoka S - J. Exp. Bot. (2015)

Ammonium sensitivity of AtNUDX9-disrupted or -suppressed Arabidopsis plants. Experimental conditions are the same as in Fig. 5. (A, B) Primary root length and relative root elongation, respectively, of the wild-type, KO-nudx9, KD-nudx9, and vtc1-1 plants grown on +NH4+and –NH4+mediums. In the data of relative root elongation, 100% corresponds to a primary root length of respective plants grown on –NH4+medium for 10 d. (C, D) Phenotypes. Scale bars, 1 and 0.5cm, respectively. The numbers (1 to 4) indicate the position of leaves. (E, F, G) Dry weight of leaves and roots, leaf area, and numbers of lateral roots of 10-d-old plants. The positions of leaves are described as in (D). Data represent means ±SD of 9–15 replicates. Values without a common letter were significantly different according to ANOVA (P <0.05). (This figure is available in colour at JXB online.)
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Figure 6: Ammonium sensitivity of AtNUDX9-disrupted or -suppressed Arabidopsis plants. Experimental conditions are the same as in Fig. 5. (A, B) Primary root length and relative root elongation, respectively, of the wild-type, KO-nudx9, KD-nudx9, and vtc1-1 plants grown on +NH4+and –NH4+mediums. In the data of relative root elongation, 100% corresponds to a primary root length of respective plants grown on –NH4+medium for 10 d. (C, D) Phenotypes. Scale bars, 1 and 0.5cm, respectively. The numbers (1 to 4) indicate the position of leaves. (E, F, G) Dry weight of leaves and roots, leaf area, and numbers of lateral roots of 10-d-old plants. The positions of leaves are described as in (D). Data represent means ±SD of 9–15 replicates. Values without a common letter were significantly different according to ANOVA (P <0.05). (This figure is available in colour at JXB online.)
Mentions: In order to determine whether AtNUDX9 was involved in NH4+sensitivity, the growth of wild-type, KO-nudx9, and KD-nudx9 plants were compared as well as the vtc1-1 mutants on the –NH4+and +NH4+media. Consistent with previous findings, root growth in the vtc1-1 mutants was inhibited more than that by the wild-type plants on the +NH4+medium (Qin et al., 2008; Barth et al., 2010) (Fig. 6A–C). No significant difference was noted in primary root length between the wild-type plants and vtc1-1 mutants on the –NH4+medium. An inverse correlation was observed between AtNUDX9 and VTC1 with regard to the effects of NH4+on root growth. The primary root lengths of the KO-nudx9 and KD-nudx9 plants were longer than those of the wild-type plants on the +NH4+medium, but not on the –NH4+medium (Fig. 6A, C). The relative primary root elongation of KO-nudx9 and KD-nudx9 was sustained even under the +NH4+medium (Fig. 6B). Furthermore, the dry weight of roots and numbers of lateral roots of the KO-nudx9 and KD-nudx9 plants on the +NH4+medium were increased compared with those of the wild-type plants (Fig. 6E, G). These results indicated that AtNUDX9 negatively modulated root growth in response to NH4+, possibly through the hydrolysis of GDP-d-Man. The aerial parts of all the genotypes tested here showed similar phenotypes on the –NH4+medium (Fig. 6C, D). On the other hand, the aerial parts of KO-nudx9 and KD-nudx9 plants were larger than the wild-type and vtc1-1 plants on the +NH4+medium. In fact, the leaf size and dry weight of aerial parts of KO-nudx9 and KD-nudx9 plants on the +NH4+medium were significantly increased compared with those of the wild-type plants (Fig. 6E, F). Considering the high expression levels of AtNUDX9 in root tissues, it is likely that the enhanced root growth in the KO-nudx9 and KD-nudx9 plants causes facilitation of the growth of aerial parts.

Bottom Line: The GDP-d-Man pyrophosphohydrolase activity was increased in the root of plants grown in the presence of ammonium.No difference was observed in the levels of AsA in the leaf and root tissues of the wild-type and knockout-nudx9 (KO-nudx9) plants, whereas a marked increase in N-glycoprotein levels and enhanced growth were detected in the roots of KO-nudx9 plants in the presence of ammonium.These results suggest that AtNUDX9 is involved in the regulation of GDP-d-Man levels affecting ammonium sensitivity via modulation of protein N-glycosylation in the roots.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.

No MeSH data available.