Abstract
Two new nitrate assimilation-related genes, Nrt2;3 and Nar5, have been identified in Chlamydomonas reinhardtii. The Nrt2;3 gene is a new member of the Nrt2 family, encoding high-affinity nitrate (nitrite) transporters. Like that of the nitrate assimilation genes, expression of the Nrt2;3 gene is down-regulated by ammonium and positively controlled by Nit2, a regulatory locus specific for the pathway. The three Nrt2 genes of C. reinhardtii are differentially regulated by the nitrogen source. Expression of Nrt2;3 and of Nrt2;1, a nitrate/nitrite-bispecific transporter gene, was induced by nitrate and more efficiently by nitrite. Accumulation of mRNA of Nrt2;2, the nitrate-specific transporter gene, was only induced efficiently by nitrate. The Nar5 gene is located upstream of the Nrt2;3 genomic region and expression of its mRNA is down-regulated by ammonium. The Nrt2;3 and Nar5 genes are overexpressed in a deletion mutant that lacks nitrate assimilation loci.
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Received: 6 October 1997 / Accepted: 30 December 1997
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Quesada, A., Hidalgo, J. & Fernández, E. Three Nrt2 genes are differentially regulated in Chlamydomonas reinhardtii . Mol Gen Genet 258, 373–377 (1998). https://doi.org/10.1007/s004380050743
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DOI: https://doi.org/10.1007/s004380050743