The photoprotective protein PsbS exerts control over CO2 assimilation rate in fluctuating light in rice
The photoprotective protein PsbS exerts control over CO2 assimilation rate in fluctuating light in rice
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DOI：
10.1111/j.1365-313x.2012.04995.x
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发表时间：
2012-08-01
期刊：
影响因子：
7.2
通讯作者：
Murchie, Erik H.
中科院分区：
文献类型：
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作者：
Hubbart, Stella;Ajigboye, Olubukola O.;Murchie, Erik H.
在没有光抑制的情况下，叶绿体保护性能量耗散(QE)对光合作用CO2同化的直接影响尚未在植物中直接表现出来。为了经验性地验证这一点，我们将水稻转化为具有较高(过表达基因，OE)和较低(RNA干扰，RNAi)表达水平的PSBS基因，并在波动的测量光照条件下分析了转化体中的二氧化碳同化作用。Western blotts显示RNAi植物和OE植物的PSBs蛋白水平存在数倍的差异，其中野生型(WT)居中。在600 mU molm-2 s-1的生长光强下，RNAi植株的羧化能力、电子传递能力和暗适应Fv/Fm(可变与最大荧光的比率)比WT和OE受到抑制。PSB含量对QE(这里测量为非光化学猝灭，NPQ)有显著影响，但最大的影响是在光照后立即观察到的瞬时效应。在光照的前10分钟，RNAi植物的QE能力要低几倍，而OE植物的QE能力则显著高于RNAi植物。在稳定状态下，差异缩小：值得注意的是，在500 mU/m~(-2)秒~(-1)时，无论PSB含量如何，所有植株的NPQ值都相同。在一系列的光暗转换过程中，OE植物CO2同化的诱导受到抑制，从而降低了光合作用。我们的结论是，PSB的积累和由此产生的QE对波动光下的光合作用起着控制作用，表明即使在没有光抑制胁迫的情况下，光保护过程的优化对于最大的光合作用生产力也是必要的。
A direct impact of chloroplastic protective energy dissipation (qE) on photosynthetic CO2 assimilation has not been shown directly in plants in the absence of photoinhibition. To test this empirically we transformed rice to possess higher (overexpressors, OE) and lower (RNA interference, RNAi) levels of expression of the regulatory psbS gene and analysed CO2 assimilation in transformants in a fluctuating measurement light regime. Western blots showed a several-fold difference in levels of PsbS protein between RNAi and OE plants with the wild type (WT) being intermediate. At a growth light intensity of 600 mu mol m-2 sec-1, the carboxylation capacity, electron transport capacity and dark adapted Fv/Fm (ratio of variable to maximum fluorescence) were inhibited in RNAi plants compared with WT and OE. The PsbS content had a significant impact on qE (measured here as non-photochemical quenching, NPQ) but the strongest effect was observed transiently, immediately following the application of light. This capacity for qE was several-fold lower in RNAi plants and significantly higher in OE plants during the first 10 min of illumination. At steady state the differences were reduced: notably at 500 mu mol m-2 sec-1 all plants had the same NPQ values regardless of PsbS content. During a series of lightdark transitions the induction of CO2 assimilation was inhibited in OE plants, reducing integrated photosynthesis during the light period. We conclude that the accumulation of PsbS and the resultant qE exerts control over photosynthesis in fluctuating light, showing that optimization of photoprotective processes is necessary for maximum photosynthetic productivity even in the absence of photoinhibitory stress.