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Nitrogen affects cluster root formation and expression of putative peptide transporters.

Paungfoo-Lonhienne C, Schenk PM, Lonhienne TG, Brackin R, Meier S, Rentsch D, Schmidt S - J. Exp. Bot. (2009)

Bottom Line: The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters.Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON.It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply.

View Article: PubMed Central - PubMed

Affiliation: School of Integrative Biology, University of Queensland, QLD, 4072, Australia. chanyarat@uq.edu.au

ABSTRACT
Non-mycorrhizal Hakea actites (Proteaceae) grows in heathland where organic nitrogen (ON) dominates the soil nitrogen (N) pool. Hakea actites uses ON for growth, but the role of cluster roots in ON acquisition is unknown. The aim of the present study was to ascertain how N form and concentration affect cluster root formation and expression of peptide transporters. Hydroponically grown plants produced most biomass with low molecular weight ON>inorganic N>high molecular weight ON, while cluster roots were formed in the order no-N>ON>inorganic N. Intact dipeptide was transported into roots and metabolized, suggesting a role for the peptide transporter (PTR) for uptake and transport of peptides. HaPTR4, a member of subgroup II of the NRT1/PTR transporter family, which contains most characterized di- and tripeptide transporters in plants, facilitated transport of di- and tripeptides when expressed in yeast. No transport activity was demonstrated for HaPTR5 and HaPTR12, most similar to less well characterized transporters in subgroup III. The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters. Green fluorescent protein fusion proteins of HaPTR4 and HaPTR12 localized to tonoplast, and plasma- and endomembranes, respectively, while HaPTR5 localized to vesicles of unknown identity. Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON. It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply.

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Time course of HaPTR expression in cluster roots. Expression levels were determined with quantitative real-time PCR and standardized using 18S rRNA. Plants were grown hydroponically in the glasshouse under nutrient starvation for 7 months and resupplied for 1, 6, 19, 24, and 72 h with protein as the N source. Data represent averages and the SD of three independent samples (two replicates where no SD is shown). Significant differences (P <0.05, one-way ANOVA, Tukey's post hoc test) are indicated with lower case (HaPTR5) and upper case letters (HaPTR12).
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fig6: Time course of HaPTR expression in cluster roots. Expression levels were determined with quantitative real-time PCR and standardized using 18S rRNA. Plants were grown hydroponically in the glasshouse under nutrient starvation for 7 months and resupplied for 1, 6, 19, 24, and 72 h with protein as the N source. Data represent averages and the SD of three independent samples (two replicates where no SD is shown). Significant differences (P <0.05, one-way ANOVA, Tukey's post hoc test) are indicated with lower case (HaPTR5) and upper case letters (HaPTR12).

Mentions: Experiment 3 was designed to examine if expression of HaPTR genes was altered in the short term in response to protein supply. Over 72 h, expression of HaPTR4 was unaltered by protein re-supply, while expression of HaPTR12 decreased after 24 h and 72 h (Fig. 6). Expression of HaPTR5 was significantly higher at 10 h than at all other times (Fig. 6).


Nitrogen affects cluster root formation and expression of putative peptide transporters.

Paungfoo-Lonhienne C, Schenk PM, Lonhienne TG, Brackin R, Meier S, Rentsch D, Schmidt S - J. Exp. Bot. (2009)

Time course of HaPTR expression in cluster roots. Expression levels were determined with quantitative real-time PCR and standardized using 18S rRNA. Plants were grown hydroponically in the glasshouse under nutrient starvation for 7 months and resupplied for 1, 6, 19, 24, and 72 h with protein as the N source. Data represent averages and the SD of three independent samples (two replicates where no SD is shown). Significant differences (P <0.05, one-way ANOVA, Tukey's post hoc test) are indicated with lower case (HaPTR5) and upper case letters (HaPTR12).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692012&req=5

fig6: Time course of HaPTR expression in cluster roots. Expression levels were determined with quantitative real-time PCR and standardized using 18S rRNA. Plants were grown hydroponically in the glasshouse under nutrient starvation for 7 months and resupplied for 1, 6, 19, 24, and 72 h with protein as the N source. Data represent averages and the SD of three independent samples (two replicates where no SD is shown). Significant differences (P <0.05, one-way ANOVA, Tukey's post hoc test) are indicated with lower case (HaPTR5) and upper case letters (HaPTR12).
Mentions: Experiment 3 was designed to examine if expression of HaPTR genes was altered in the short term in response to protein supply. Over 72 h, expression of HaPTR4 was unaltered by protein re-supply, while expression of HaPTR12 decreased after 24 h and 72 h (Fig. 6). Expression of HaPTR5 was significantly higher at 10 h than at all other times (Fig. 6).

Bottom Line: The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters.Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON.It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply.

View Article: PubMed Central - PubMed

Affiliation: School of Integrative Biology, University of Queensland, QLD, 4072, Australia. chanyarat@uq.edu.au

ABSTRACT
Non-mycorrhizal Hakea actites (Proteaceae) grows in heathland where organic nitrogen (ON) dominates the soil nitrogen (N) pool. Hakea actites uses ON for growth, but the role of cluster roots in ON acquisition is unknown. The aim of the present study was to ascertain how N form and concentration affect cluster root formation and expression of peptide transporters. Hydroponically grown plants produced most biomass with low molecular weight ON>inorganic N>high molecular weight ON, while cluster roots were formed in the order no-N>ON>inorganic N. Intact dipeptide was transported into roots and metabolized, suggesting a role for the peptide transporter (PTR) for uptake and transport of peptides. HaPTR4, a member of subgroup II of the NRT1/PTR transporter family, which contains most characterized di- and tripeptide transporters in plants, facilitated transport of di- and tripeptides when expressed in yeast. No transport activity was demonstrated for HaPTR5 and HaPTR12, most similar to less well characterized transporters in subgroup III. The results provide further evidence that subgroup II of the NRT1/PTR family contains functional di- and tripeptide transporters. Green fluorescent protein fusion proteins of HaPTR4 and HaPTR12 localized to tonoplast, and plasma- and endomembranes, respectively, while HaPTR5 localized to vesicles of unknown identity. Grown in heathland or hydroponic culture with limiting N supply or starved of nutrients, HaPTR genes had the highest expression in cluster roots and non-cluster roots, and leaf expression increased upon re-supply of ON. It is concluded that formation of cluster roots and expression of PTR are regulated in response to N supply.

Show MeSH
Related in: MedlinePlus