AUTHOR=Ilikchyan Irina N., Mckay Robert M., Kutovaya Olga A., Condon Rob , Bullerjahn George S.

TITLE=Seasonal Expression of the Picocyanobacterial Phosphonate Transporter Gene phnD in the Sargasso Sea

JOURNAL=Frontiers in Microbiology

VOLUME=1

YEAR=2010

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2010.00135

DOI=10.3389/fmicb.2010.00135

ISSN=1664-302X

ABSTRACT=<p>In phosphorus-limited marine environments, picocyanobacteria (<italic>Synechococcus</italic> and <italic>Prochlorococcus</italic> spp.) can hydrolyze naturally occurring phosphonates as a P source. Utilization of 2-aminoethylphosphonate (2-AEP) is dependent on expression of the <italic>phn</italic> genes, encoding functions required for uptake, and C–P bond cleavage. Prior work has indicated that expression of picocyanobacterial <italic>phnD</italic>, encoding the phosphonate binding protein of the phosphonate ABC transporter, is a proxy for the assimilation of phosphonates in natural assemblages of <italic>Synechococcus</italic> spp. and <italic>Prochlorococcus</italic> spp (Ilikchyan et al., <xref ref-type="bibr" rid="B17">2009</xref>). In this study, we expand this work to assess seasonal <italic>phnD</italic> expression in the Sargasso Sea. By RT-PCR, our data confirm that <italic>phnD</italic> expression is constitutive for the <italic>Prochlorococcus</italic> spp. detected, but in <italic>Synechococcus</italic> spp. <italic>phnD</italic> transcription follows patterns of phosphorus availability in the mixed layer. Specifically, our data suggest that <italic>phnD</italic> is repressed in the spring when P is bioavailable following deep winter mixing. In the fall, <italic>phnD</italic> expression follows a depth-dependent pattern reflecting depleted P at the surface following summertime drawdown, and elevated P at depth.</p>