PMID:22858636

Citation	Bagchi, R, Salehin, M, Adeyemo, OS, Salazar, C, Shulaev, V, Sherrier, DJ and Dickstein, R (2012) Functional Assessment of the Medicago truncatula NIP/LATD Protein Demonstrates That It Is a High-Affinity Nitrate Transporter. Plant Physiol. 160:906-16
Abstract	The Medicago truncatula NIP/LATD (for Numerous Infections and Polyphenolics/Lateral root-organ Defective) gene encodes a protein found in a clade of nitrate transporters within the large NRT1(PTR) family that also encodes transporters of dipeptides and tripeptides, dicarboxylates, auxin, and abscisic acid. Of the NRT1(PTR) members known to transport nitrate, most are low-affinity transporters. Here, we show that M. truncatula nip/latd mutants are more defective in their lateral root responses to nitrate provided at low (250 μm) concentrations than at higher (5 mm) concentrations; however, nitrate uptake experiments showed no discernible differences in uptake in the mutants. Heterologous expression experiments showed that MtNIP/LATD encodes a nitrate transporter: expression in Xenopus laevis oocytes conferred upon the oocytes the ability to take up nitrate from the medium with high affinity, and expression of MtNIP/LATD in an Arabidopsis chl1(nrt1.1) mutant rescued the chlorate susceptibility phenotype. X. laevis oocytes expressing mutant Mtnip-1 and Mtlatd were unable to take up nitrate from the medium, but oocytes expressing the less severe Mtnip-3 allele were proficient in nitrate transport. M. truncatula nip/latd mutants have pleiotropic defects in nodulation and root architecture. Expression of the Arabidopsis NRT1.1 gene in mutant Mtnip-1 roots partially rescued Mtnip-1 for root architecture defects but not for nodulation defects. This suggests that the spectrum of activities inherent in AtNRT1.1 is different from that possessed by MtNIP/LATD, but it could also reflect stability differences of each protein in M. truncatula. Collectively, the data show that MtNIP/LATD is a high-affinity nitrate transporter and suggest that it could have another function.
Links	PubMed PMC3461564 Online version:10.1104/pp.112.196444
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MEDTR:D2IU94		GO:0010015: root morphogenesis	ECO:0000315:		P		Figure 6	complete CACAO 5509
MEDTR:D2IU94		GO:0042128: nitrate assimilation	ECO:0000315:		P		Figure 1	complete CACAO 5507
MEDTR:D2IU94		GO:0015112: nitrate transmembrane transporter activity	ECO:0000314:		F		Figure 3 shows that X. laevis oocytes that express the M. truncatula protein take in nitrate from their media.	complete CACAO 5356
MEDTR:D2IU94	involved_in	GO:0042128: nitrate assimilation	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
MEDTR:D2IU94	involved_in	GO:0010015: root morphogenesis	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
MEDTR:D2IU94	enables	GO:0015112: nitrate transmembrane transporter activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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