TITLE:
Difference in Nitrogen Starvation-Inducible Expression Patterns among Phylogenetically Diverse Ammonium Transporter Genes in the Red Seaweed Pyropia yezoensis
AUTHORS:
Chengze Li, Inori Ariga, Koji Mikami
KEYWORDS:
Ammonium Transporter, Discoloration, Nitrogen, Pyropia yezoensis
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.10 No.8,
August
23,
2019
ABSTRACT: Nitrogen deficiency induces senescence and the
expression of genes encoding ammonium transporters (AMTs) in terrestrial plants
where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen
starvation in the red seaweed Pyropia yezoensis causes senescence-like discoloration. In this study, we identified five genes in P. yezoensis encoding AMT domain-containing
proteins, which
were phylogenetically categorized into the AMT1 subfamily. We also found a gene
encoding a Rhesus protein (Rh) that was related to, but diverged from, AMTs. Moreover, our phylogenetic
analysis showed that AMT domain-containing proteins from micro- and macro-algae
belonged to either the AMT1 or Rh subfamily, indicating the absence of AMT2 in
algae. Gene expression analyses
revealed the presence of gametophyte- and sporophyte-specific AMT1 genes that were
up-regulated transiently and continually,
respectively, under nitrogen-deficient conditions. In addition, up-regulated
sporophyte-specific gene expression was suppressed when nitrogen was resupplied.
Accordingly, an expansion of the ancient AMT gene has produced AMT1 functional variants differing in
temporal and nitrogen starvation-inducible expression patterns during the life cycle of P. yezoensis. These findings help elucidate the unique nutrition
starvation responses involving functionally diverse AMT1 and Rh subfamilies in
red seaweed.