High-affinity nitrate/nitrite transporter genes (Nrt2) in Tisochrysis lutea: identification and expression analyses reveal some interesting specificities of Haptophyta microalgae

Type Article
Date 2015-08
Language English
Author(s) Charrier Aurelie Georgette1, Berard Jean-BaptisteORCID1, Bougaran GaelORCID1, Carrier GregoryORCID1, Lukomska Ewa1, Schreiber Nathalie1, Fournier Flora1, Charrier Aurelie1, Rouxel Catherine1, Garnier Matthieu1, Cadoret Jean-Paul1, Saint-Jean Bruno1
Affiliation(s) 1 : IFREMER, Physiol & Biotechnol Algae Lab, F-44311 Nantes, France.
Source Physiologia Plantarum (0031-9317) (Wiley-blackwell), 2015-08 , Vol. 154 , N. 4 , P. 572-590
DOI 10.1111/ppl.12330
WOS© Times Cited 6
Abstract Microalgae have a diversity of industrial applications such as feed, food ingredients, depuration processes and energy. However, microalgal production costs could be substantially improved by controlling nutrient intake. Accordingly, a better understanding of microalgal nitrogen metabolism is essential. Using in silico analysis from transcriptomic data concerning the microalgae Tisochrysis lutea, four genes encoding putative high-affinity nitrate/nitrite transporters (TlNrt2) were identified. Unlike most of the land plants and microalgae, cloning of genomic sequences and their alignment with complementary DNA (cDNA) sequences did not reveal the presence of introns in all TlNrt2 genes. The deduced TlNRT2 protein sequences showed similarities to NRT2 proteins of other phyla such as land plants and green algae. However, some interesting specificities only known among Haptophyta were also revealed, especially an additional sequence of 100 amino acids forming an atypical extracellular loop located between transmembrane domains 9 and 10 and the function of which remains to be elucidated. Analyses of individual TlNrt2 gene expression with different nitrogen sources and concentrations were performed. TlNrt2.1 and TlNrt2.3 were strongly induced by low NO3− concentration and repressed by NH4+ substrate and were classified as inducible genes. TlNrt2.2 was characterized by a constitutive pattern whatever the substrate. Finally, TlNrt2.4 displayed an atypical response that was not reported earlier in literature. Interestingly, expression of TlNrt2.4 was rather related to internal nitrogen quota level than external nitrogen concentration. This first study on nitrogen metabolism of T. lutea opens avenues for future investigations on the function of these genes and their implication for industrial applications.
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Charrier Aurelie Georgette, Berard Jean-Baptiste, Bougaran Gael, Carrier Gregory, Lukomska Ewa, Schreiber Nathalie, Fournier Flora, Charrier Aurelie, Rouxel Catherine, Garnier Matthieu, Cadoret Jean-Paul, Saint-Jean Bruno (2015). High-affinity nitrate/nitrite transporter genes (Nrt2) in Tisochrysis lutea: identification and expression analyses reveal some interesting specificities of Haptophyta microalgae. Physiologia Plantarum, 154(4), 572-590. Publisher's official version : https://doi.org/10.1111/ppl.12330 , Open Access version : https://archimer.ifremer.fr/doc/00253/36467/