Abstract
The light-harvesting protein complexes (Lhc) play key roles in the processes of light absorption and protection in diatoms. However, different Lhc protein carries out distinct function in photosynthesis. For now, roles of many Lhc proteins in light acclimation are largely unknown. Here, function of Lhcx3 in marine diatom Phaeodactylum tricornutum was examined by using reverse genetic technologies. The overexpression of Lhcx3 led to increased diadinoxanthin + diatoxanthin content and elevated non-photochemical fluorescence quenching (NPQ) while knockdown of Lhcx3 reduced NPQ level. In addition, the expression of Lhcx3 could be induced by blue light but not by red light. After addition of the photosynthetic inhibitor, upregulation of Lhcx3 transcript in high light could be inhibited by NH4Cl, but not by DCMU (3-(3,4-dichlorophenyl)-l,l-dim ethylurea). In contrast, DCMU addition increased expression of Lhcx3 in high light. In combination with changes of NPQ after addition of inhibitor, we concluded that the Lhcx3 played key roles in high light acclimation of diatoms. This finding will provide new clues for genetic improvement of P. tricornutum with an aim to cultivate new strains with high growth rate.
Highlights
Diatoms are eukaryotic unicellular microalgae, and widely distributed in various marine environments (Field et al 1998)
Small difference of amino acid could be observed for the conserved domain of chlorophyll a/b-binding by aligning with other Lhcx proteins
Phylogenetic analysis showed that the PtLhcx3 (XP 002178699.1) had high similarity with the protein (XP 003079276.1) of Ostreococcus tauri (Fig. 1b)
Summary
Diatoms are eukaryotic unicellular microalgae, and widely distributed in various marine environments (Field et al 1998). Diatoms exhibit optimal photosynthetic activity over an extensive range of environments (Litchman et al 2009). Their excellent adaptive capacity to changing conditions is regarded as a key reason why diatoms are predominant in contemporary oceans (Field et al 1998). The key mechanism for the modulation of diatom photosynthesis is NPQ (Ruban and Murchie 2012) It occurs in the light-harvesting complex (Lhc) of PSII (Ruban and Murchie 2012). The roles of the other members of the Lhcx family in P. tricornutum were studied by using transgenic lines overexpressing the Lhcx proteins, revealing that
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call