Flavodiiron proteins enhance the rate of CO2 assimilation in Arabidopsis under fluctuating light intensity
Flavodiiron proteins enhance the rate of CO2 assimilation in Arabidopsis under fluctuating light intensity
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DOI：
10.1093/plphys/kiac064
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发表时间：
2022-02-16
期刊：
影响因子：
7.4
通讯作者：
Shikanai, Toshiharu
中科院分区：
文献类型：
--
作者：
Basso, Leonardo;Sakoda, Kazuma;Shikanai, Toshiharu
在类囊体膜上形成的质子浓度梯度（pH）和膜电位（psi）有助于叶绿体中ATP的合成。此外，δ pH降低通过类囊体腔酸化的光合电子传递。K+交换反转运蛋白3 （KEA3）通过用δ psi代替δ pH来响应光强的波动，从而缓解了这种下调。在过表达KEA3 （KEA3ox）的拟南芥（Arabidopsis thaliana）系中，从强光（HL）到弱光（HL）转换后，通过加速δ pH的弛豫来提高电子传递速率。然而，植物无法控制电子向光系统I （PSI）的传递，从而导致PSI光损伤。在本研究中，我们将KEA3ox系与表达专利立胞菌Flv蛋白的系（Flavodiiron [Flv]）杂交。在双转基因系（Flv- kea3ox）中，向PSI过载的电子被Flv蛋白泵出。因此，PSI的光损伤减轻到野生型水平。在光照波动期间，Flv和Flv- kea3ox系的CO2固定率提高，而在恒光照条件下，任何转基因系的CO2固定率均不受影响。在波动光下，CO2固定的上调伴随着气孔导度的升高。与气体交换实验结果一致，在波动光下，Flv和Flv-KEA3ox植株的生长优于WT和KEA3ox植株。在过表达K+交换反转运蛋白3的拟南芥中，黄二铁蛋白减轻了光系统I的光损伤，提高了波动光下CO2的固定速率。
The proton concentration gradient (Delta pH) and membrane potential (Delta psi) formed across the thylakoid membrane contribute to ATP synthesis in chloroplasts. Additionally, Delta pH downregulates photosynthetic electron transport via the acidification of the thylakoid lumen. K+ exchange antiporter 3 (KEA3) relaxes this downregulation by substituting Delta pH with Delta psi in response to fluctuation of light intensity. In the Arabidopsis (Arabidopsis thaliana) line overexpressing KEA3 (KEA3ox), the rate of electron transport is elevated by accelerating the relaxation of Delta pH after a shift from high light (HL) to low light. However, the plant cannot control electron transport toward photosystem I (PSI), resulting in PSI photodamage. In this study, we crossed the KEA3ox line with the line (Flavodiiron [Flv]) expressing the Flv proteins of Physcomitrium patens. In the double transgenic line (Flv-KEA3ox), electrons overloading toward PSI were pumped out by Flv proteins. Consequently, photodamage of PSI was alleviated to the wild-type level. The rate of CO2 fixation was enhanced in Flv and Flv-KEA3ox lines during HL periods of fluctuating light, although CO2 fixation was unaffected in any transgenic lines in constant HL. Upregulation of CO2 fixation was accompanied by elevated stomatal conductance in fluctuating light. Consistent with the results of gas exchange experiments, the growth of Flv and Flv-KEA3ox plants was better than that of WT and KEA3ox plants under fluctuating light.Flavodiiron proteins alleviated the photodamage of photosystem I and enhanced the rate of CO2 fixation under fluctuating light in the Arabidopsis plants overexpressing K+ exchange antiporter 3.