Isolation and functional characterization of a high affinity urea transporter from roots of Zea mays

BMC Plant Biology

Research Article

Laura Zanin¹  Nicola Tomasi¹  Roberto Pinton¹  Stefano Cesco²  Tanja Mimmo²  Corina Wirdnam³  Doris Rentsch³  Stefan Meier³  Nataliya Y Komarova³ 

[1] Dipartimento di Scienze Agrarie e Ambientali, University of Udine, via delle Scienze 208, I-33100, Udine, Italy;Faculty of Science and Technology, Free University of Bolzano, Piazza Università 5, I-39100, Bolzano, Italy;Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013, Bern, Switzerland;

关键词: Corn;    High affinity transport system;    DUR3;    Maize;    Nitrogen (N);    Root;    Urea;   

DOI  :  10.1186/s12870-014-0222-6

 received in 2014-05-12, accepted in 2014-08-06,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundDespite its extensive use as a nitrogen fertilizer, the role of urea as a directly accessible nitrogen source for crop plants is still poorly understood. So far, the physiological and molecular aspects of urea acquisition have been investigated only in few plant species highlighting the importance of a high-affinity transport system. With respect to maize, a worldwide-cultivated crop requiring high amounts of nitrogen fertilizer, the mechanisms involved in the transport of urea have not yet been identified. The aim of the present work was to characterize the high-affinity urea transport system in maize roots and to identify the high affinity urea transporter.ResultsKinetic characterization of urea uptake (<300μM) demonstrated the presence in maize roots of a high-affinity and saturable transport system; this system is inducible by urea itself showing higher Vmax and Km upon induction. At molecular level, the ORF sequence coding for the urea transporter, ZmDUR3, was isolated and functionally characterized using different heterologous systems: a dur3 yeast mutant strain, tobacco protoplasts and a dur3 Arabidopsis mutant. The expression of the isolated sequence, ZmDUR3-ORF, in dur3 yeast mutant demonstrated the ability of the encoded protein to mediate urea uptake into cells. The subcellular targeting of DUR3/GFP fusion proteins in tobacco protoplasts gave results comparable to the localization of the orthologous transporters of Arabidopsis and rice, suggesting a partial localization at the plasma membrane. Moreover, the overexpression of ZmDUR3 in the atdur3-3 Arabidopsis mutant showed to complement the phenotype, since different ZmDUR3-overexpressing lines showed either comparable or enhanced 15[N]-urea influx than wild-type plants. These data provide a clear evidence in planta for a role of ZmDUR3 in urea acquisition from an extra-radical solution.ConclusionsThis work highlights the capability of maize plants to take up urea via an inducible and high-affinity transport system. ZmDUR3 is a high-affinity urea transporter mediating the uptake of this molecule into roots. Data may provide a key to better understand the mechanisms involved in urea acquisition and contribute to deepen the knowledge on the overall nitrogen-use efficiency in crop plants.

【 授权许可】

CC BY   
© Zanin et al.; licensee BioMed Central Ltd. 2014