Mutation of a nitrate transporter, AtNRT1:4, results in a reduced petiole nitrate content and altered leaf development.
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.
Chiu
Chi-Chou
CC
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
Lin
Choun-Sea
CS
Hsia
An-Ping
AP
Su
Ruey-Chih
RC
Lin
Huey-Ling
HL
Tsay
Yi-Fang
YF
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
D027321:Anion Transport Proteins; D017931:DNA Primers; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010940:Plant Proteins