Production of ketocarotenoids in tobacco alters the photosynthetic efficiency by reducing photosystem II supercomplex and LHCII trimer stability
Production of ketocarotenoids in tobacco alters the photosynthetic efficiency by reducing photosystem II supercomplex and LHCII trimer stability
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DOI：
10.1007/s11120-014-0055-z
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
Anja Röding;Lars Dietzel;Hagen Schlicke;B. Grimm;G. Sandmann;C. Büchel
中科院分区：
文献类型：
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作者：
Anja Röding;Lars Dietzel;Hagen Schlicke;B. Grimm;G. Sandmann;C. Büchel
研究了转基因烟草（Nicotiana tabacum）中酮类胡萝卜素产生的后果，所述转基因烟草表达编码β-胡萝卜素酮醇酶的莱茵衣藻基因，所述后果与光合机构的功能有关。T1植株单位干重光合色素产量减少，但叶绿素a/叶绿素B比值保持不变。几乎一样多的酮类胡萝卜素作为辅助叶黄素积累每叶绿素a分子。这些酮类胡萝卜素被发现主要在类囊体膜，但没有功能绑定到捕光复合物，虽然LHCII是已知的能够结合虾青素。相反，大量的酮类胡萝卜素可能改变了类囊体的脂质相的性质，从而降低了光系统II超复合物和LHCII三聚体的稳定性，并最终减少基粒的形成。此外，光系统II的电子传递功能受损，植物表现出较少的非光化学猝灭相比，野生型植物。因此，为了不干扰植物的重要功能，虾青素和其它营养上有价值的酮类胡萝卜素的生产显然需要将额外的类胡萝卜素螯合到质体中的方法。
The consequences of ketocarotenoid production in transgenic tobacco (Nicotiana tabacum) plants expressing aChlamydomonas reinhardtiigene encoding a β-carotene ketolase were examined concerning the functionality of the photosynthetic apparatus. T1 plants produced less photosynthetic pigments per dry weight, but Chl a/Chl b ratios remained unchanged. Almost as much ketocarotenoids as accessory xanthophylls accumulated per Chl a molecule. These ketocarotenoids were found mainly in the thylakoid membranes, but were not functionally bound to light-harvesting complexes, although LHCII is known to be able to bind astaxanthin. On the contrary, high amounts of ketocarotenoids probably changed the properties of the lipid phase of the thylakoids, thereby reducing the stability of photosystem II supercomplexes and LHCII trimers and ultimately decreasing grana formation. In addition, photosystem II function in electron transport was impaired, and plants exhibited less non-photochemical quenching compared to wild-type plants. Thus, in order not to disturb vital functions of the plants, production of astaxanthin and other nutritionally valuable ketocarotenoids apparently requires ways to sequester the additional carotenoids to plastoglobuli.