Ware Maxwell A, Dall'Osto Luca, Ruban Alexander V
School of Biological and Chemical Sciences, Queen Mary University of London London, UK.
Dipartimento di Biotecnologie, Università di Verona Verona, Italy.
Front Plant Sci. 2016 Jun 21;7:841. doi: 10.3389/fpls.2016.00841. eCollection 2016.
Contribution of different LHCII antenna carotenoids to protective NPQ (pNPQ) were tested using a range of xanthophyll biosynthesis mutants of Arabidopsis: plants were either devoid of lutein (lut2), violaxanthin (npq2), or synthesized a single xanthophyll species, namely violaxanthin (aba4npq1lut2), zeaxanthin (npq2lut2), or lutein (chy1chy2lut5). A novel pulse amplitude modulated (PAM) fluorescence analysis procedure, that used a gradually increasing actinic light intensity, allowed the efficiency of pNPQ to be tested using the photochemical quenching (qP) parameter measured in the dark (qPd). Furthermore, the yield of photosystem II (ΦPSII) was calculated, and the light intensity which induces photoinhibition in 50% of leaves for each mutant was ascertained. Photoprotective capacities of each xanthophyll were quantified, taking into account chlorophyll a/b ratios and excitation pressure. Here, light tolerance, pNPQ capacity, and ΦPSII were highest in wild type plants. Of the carotenoid mutants, lut2 (lutein-deficient) plants had the highest light tolerance, and the joint the highest ΦPSII with violaxanthin only plants. We conclude that all studied mutants possess pNPQ and a more complete composition of xanthophylls in their natural binding sites is the most important factor governing photoprotection, rather than any one specific xanthophyll suggesting a strong structural effect of the molecules upon the LHCII antenna organization and discuss the results significance for future crop development.
利用一系列拟南芥叶黄素生物合成突变体，测试了不同LHCII天线类胡萝卜素对保护性非光化学猝灭（pNPQ）的贡献：这些植物要么缺乏叶黄素（lut2）、紫黄质（npq2），要么只合成一种叶黄素，即紫黄质（aba4npq1lut2）、玉米黄质（npq2lut2）或叶黄素（chy1chy2lut5）。一种新颖的脉冲幅度调制（PAM）荧光分析程序，使用逐渐增加的光化光强度，允许使用在黑暗中测量的光化学猝灭（qP）参数（qPd）来测试pNPQ的效率。此外，计算了光系统II的量子产率（ΦPSII），并确定了每个突变体在50%叶片中诱导光抑制的光强度。考虑到叶绿素a/b比值和激发压力，对每种叶黄素的光保护能力进行了量化。在这里，野生型植物的耐光性、pNPQ能力和ΦPSII最高。在类胡萝卜素突变体中，lut2（缺乏叶黄素）植物具有最高的耐光性，并且与仅含紫黄质的植物共同具有最高的ΦPSII。我们得出结论，所有研究的突变体都具有pNPQ，并且叶黄素在其天然结合位点的更完整组成是控制光保护的最重要因素，而不是任何一种特定的叶黄素，这表明这些分子对LHCII天线组织具有强烈的结构效应，并讨论了这些结果对未来作物发育的意义。
