An atypical member of the light-harvesting complex stress-related protein family modulates diatom responses to light

• DOI: 10.1073/pnas.1007703107
• Publication Date: 2010-10-05T02:41:48Z
• Authors: Benjamin Bailleul; Alessandra Rogato; Alessandra de Mar...; Sacha Coesel; Pierre Cardol; Chris Bowler; Angela Falciatore; Giovanni Finazzi
• Keywords: llight acclimation; Chlorophyll; 0301 basic medicine; 570; MESH: Light-Harvesting Protein Complexes; Light; [SDV.BBM]Life Sciences [q-bio]/Biochemistry; ecotypes; Light-Harvesting Protein Complexes; Phaeodactylum tricornutum; LHCX; diatoms; stress; light acclimation; 03 medical and health sciences; RNA interference; [SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology; MESH: Gene Silencing; [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology; photoresponse; Gene Silencing; 14. Life underwater; Molecular Biology; Diatoms; light harvesting complex; photosynthesis; MESH: Gene Knockdown Techniques; MESH: Light; diatom; nonphotochemical quenching; Oxygen; Gene Knockdown Techniques; phytoplankton; gene expression; MESH: Chlorophyll; MESH: Diatoms; MESH: Oxygen

Diatoms are prominent phytoplanktonic organisms that contribute around 40% of carbon assimilation in the oceans. They grow and perform optimally in variable environments, being able to cope with unpredictable changes in the amount and quality of light. The molecular mechanisms regulating diatom light responses are, however, still obscure. Using knockdown Phaeodactylum tricornutum transgenic lines, we reveal the key function of a member of the light-harvesting complex stress-related (LHCSR) protein family, denoted LHCX1, in modulation of excess light energy dissipation. In contrast to green algae, this gene is already maximally expressed in nonstressful light conditions and encodes a protein required for efficient light responses and growth. LHCX1 also influences natural variability in photoresponse, as evidenced in ecotypes isolated from different latitudes that display different LHCX1 protein levels. We conclude, therefore, that this gene plays a pivotal role in managing light responses in diatoms.