Previous work showed in tomato plants harbouring the Agrobacterium rhizogenes rolB gene overexpression of genes involved in chloroplast function and stress response, significant increase in non-photochemical quenching and chlorophyll a and b content, and reduced chlorophyll a/b ratio. The latter condition being typical of plant shade where far-red is dominant, suggested a role for rolB in improving photosynthesis in such condition. To gain a better insight into these results, the photosynthetic performance of transgenic and control plants was compared by means of variable fluorescence kinetics with a WATER-PAM chlorophyll fluorometer, after 6 days-exposure to white light and to a far-red-enriched light source. Photosynthetic parameters analysed were quantum yield of photosystem II photochemistry Y(II); qL, corresponding to the fraction of open PSII reaction centers in a "lake" model of photosystem II; non-photochemical quenching and Y(NO), describing, respectively, regulated and non-regulated pathways for dissipation of excess energy. Chlorophyll a and b content was also analysed by HPLC. Finally, real-time PCR was performed to quantify the expression level of some of the chloroplast-related genes already shown to be overexpressed in transgenic plants. Quantum yield of photosystem II photochemistry decreased with increasing light intensity, showing no significant differences in both plant genotypes and light regimen. qL, on the other hand, was significantly higher at low PAR intensities, in particular in FR-treated transgenic plants. Fate of remaining light energy, channelled into regulated or non-regulated dissipation pathways, was different in transgenic and control plants, indicating a higher capability for protection from photodamage in rolB plants, particularly after exposure to far-red-enriched light. Chlorophyll a/b ratio was also decreased in transgenic plants under far-red-enriched light with respect to white light. Finally, qPCR showed that the expression of genes encoding small heat shock protein, chlorophyll a/b binding protein and carbonic anhydrase was significantly induced by far-red-enriched condition. Taken together, these data suggest the involvement of rolB in photosynthesis modulation under far-red-rich light in tomato.

中文翻译：

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远红光照射对转基因发根农杆菌rolB基因番茄植株光合作用和光保护的影响

先前的工作表明，在含有发根农杆菌 rolB 基因的番茄植物中，与叶绿体功能和应激反应相关的基因过表达，非光化学猝灭和叶绿素 a 和 b 含量显着增加，并降低了叶绿素 a/b 比率。后一种情况是典型的植物遮荫，其中远红色占主导地位，表明 rolB 在这种情况下在改善光合作用方面发挥了作用。为了更好地了解这些结果，在暴露于白光和富含远红光 6 天后，通过可变荧光动力学与 WATER-PAM 叶绿素荧光计比较了转基因植物和对照植物的光合性能来源。分析的光合参数是光系统II光化学Y(II)的量子产率；qL, 对应于光系统 II 的“湖”模型中开放 PSII 反应中心的比例；非光化学猝灭和 Y(NO)，分别描述了多余能量耗散的调节和非调节途径。叶绿素 a 和 b 的含量也通过 HPLC 进行了分析。最后，进行实时 PCR 以量化一些叶绿体相关基因的表达水平，这些基因已经显示在转基因植物中过度表达。光系统 II 光化学的量子产率随着光照强度的增加而降低，在植物基因型和光照方案中没有显着差异。另一方面，qL 在低 PAR 强度下显着更高，尤其是在 FR 处理的转基因植物中。剩余光能的命运，被引导到受调节或不受调节的耗散途径，在转基因植物和对照植物中不同，表明 rolB 植物具有更高的保护免受光损伤的能力，尤其是在暴露于富含远红光的光下之后。相对于白光，在富含远红光的光下，转基因植物中的叶绿素 a/b 比率也降低。最后，qPCR显示远红富集条件显着诱导编码小热休克蛋白、叶绿素a/b结合蛋白和碳酸酐酶的基因的表达。总之，这些数据表明 rolB 参与了番茄在远红光下的光合作用调节。相对于白光，在富含远红光的光下，转基因植物中的叶绿素 a/b 比率也降低。最后，qPCR显示远红富集条件显着诱导编码小热休克蛋白、叶绿素a/b结合蛋白和碳酸酐酶的基因的表达。总之，这些数据表明 rolB 参与了番茄在远红光下的光合作用调节。相对于白光，在富含远红光的光下，转基因植物中的叶绿素 a/b 比率也降低。最后，qPCR显示远红富集条件显着诱导编码小热休克蛋白、叶绿素a/b结合蛋白和碳酸酐酶的基因的表达。总之，这些数据表明 rolB 参与了番茄在远红光下的光合作用调节。