Hao Ting-Bin, Jiang Tao, Dong Hong-Po, Ou Lin-Jian, He Xiang, Yang Yu-Feng
Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science, Jinan University, Guangzhou, 510632, China.
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China.
AMB Express. 2018 Oct 23;8(1):174. doi: 10.1186/s13568-018-0703-3.
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 NHCl, 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.
光捕获蛋白复合体（Lhc）在硅藻的光吸收和保护过程中发挥着关键作用。然而，不同的Lhc蛋白在光合作用中执行不同的功能。目前，许多Lhc蛋白在光适应中的作用很大程度上尚不清楚。在此，利用反向遗传技术研究了海洋硅藻三角褐指藻中Lhcx3的功能。Lhcx3的过表达导致二甲基丙烯基二甲基烯丙基二硫醚+二甲基丙烯基二甲基烯丙基二硫醚含量增加和非光化学荧光猝灭（NPQ）升高，而Lhcx3的敲低则降低了NPQ水平。此外，Lhcx3的表达可被蓝光诱导，但不能被红光诱导。添加光合抑制剂后，高光下Lhcx3转录本的上调可被NHCl抑制，但不能被DCMU（3-(3,4-二氯苯基)-1,1-二甲基脲）抑制。相反，添加DCMU会增加高光下Lhcx3的表达。结合添加抑制剂后NPQ的变化，我们得出结论，Lhcx3在硅藻的高光适应中起关键作用。这一发现将为三角褐指藻的遗传改良提供新线索，旨在培育高生长速率的新菌株。
