title: Mutation of a nitrate transporter, AtNRT1:4, results in a reduced petiole nitrate content and altered leaf development.
abstract: Unlike nitrate uptake of plant roots, less is known at the molecular level about how nitrate is distributed in various plant tissues. In the present study, characterization of the nitrate transporter, AtNRT1:4, revealed a special role of petiole in nitrate homeostasis. Electrophysiological studies using Xenopus oocytes showed that AtNRT1:4 was a low-affinity nitrate transporter. Whole-mount in situ hybridization and RT-PCR demonstrated that AtNRT1:4 was expressed in the leaf petiole. In the wild type, the leaf petiole had low nitrate reductase activity, but a high nitrate content, indicating that it is the storage site for nitrate, whereas, in the atnrt1:4 mutant, the petiole nitrate content was reduced to 50-64% of the wild-type level. Moreover, atnrt1:4 mutant leaves were wider than wild-type leaves. This study revealed a critical role of AtNRT1:4 in regulating leaf nitrate homeostasis, and the deficiency of AtNRT1:4 can alter leaf development.
authors.affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chi-Chou
authors.initials: CC
authors.lastname: Chiu
authors.forename: Choun-Sea
authors.initials: CS
authors.lastname: Lin
authors.forename: An-Ping
authors.initials: AP
authors.lastname: Hsia
authors.forename: Ruey-Chih
authors.initials: RC
authors.lastname: Su
authors.forename: Huey-Ling
authors.initials: HL
authors.lastname: Lin
authors.forename: Yi-Fang
authors.initials: YF
authors.lastname: Tsay
mesh_terms: D027321:Anion Transport Proteins / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D017403:In Situ Hybridization; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D027321:Anion Transport Proteins; D017931:DNA Primers; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010940:Plant Proteins