Photosynthesis of Root Chloroplasts Developed in Arabidopsis Lines Overexpressing GOLDEN2-LIKE Transcription Factors
Photosynthesis of Root Chloroplasts Developed in Arabidopsis Lines Overexpressing GOLDEN2-LIKE Transcription Factors
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DOI：
10.1093/pcp/pct086
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发表时间：
2013-08-01
影响因子：
4.9
通讯作者：
Masuda, Tatsuru
中科院分区：
文献类型：
--
作者：
Kobayashi, Koichi;Sasaki, Daichi;Masuda, Tatsuru
在植物中，参与光合作用的基因分别在细胞核和质体中编码，因此这两个基因组之间的紧密合作是功能叶绿体发育所必需的。Golden 2-like（GLK）转录因子参与叶绿体发育，直接靶向光合相关的核基因进行上调。虽然GLK的过表达导致叶绿体发育在非光合器官，GLK影响的核基因表达和叶绿体内的光合过程之间的协调机制在很大程度上是未知的。为了阐明GLK诱导的光合相关核基因表达对光合系统构建的影响，将过表达GLK的拟南芥品系的绿色根中的叶绿体形态和光合特性与野生型根和叶中的叶绿体形态和光合特性进行了比较。GLK的过表达不仅引起其直接靶基因的上调，而且引起非靶核基因和质体基因的上调，从而导致根中叶绿体生物发生的整体诱导。在野生型根中观察到相对于反应中心的大触角，并且由于与外围捕光触角相关的靶基因的表达增加而通过GLK过表达进一步增强。根叶绿体的光化学效率低于叶叶绿体，表明光合机制的不平衡降低了根叶绿体的光利用效率。尽管光化学效率较低，但拟南芥根系光合作用对碳同化有贡献。此外，GLK过表达增加了CO2固定，促进了根系的光合性能，显示了根系光合作用提高植物有效碳利用的潜力。
In plants, genes involved in photosynthesis are encoded separately in nuclei and plastids, and tight cooperation between these two genomes is therefore required for the development of functional chloroplasts. Golden2-like (GLK) transcription factors are involved in chloroplast development, directly targeting photosynthesis-associated nuclear genes for up-regulation. Although overexpression of GLKs leads to chloroplast development in non-photosynthetic organs, the mechanisms of coordination between the nuclear gene expression influenced by GLKs and the photosynthetic processes inside chloroplasts are largely unknown. To elucidate the impact of GLK-induced expression of photosynthesis-associated nuclear genes on the construction of photosynthetic systems, chloroplast morphology and photosynthetic characteristics in greenish roots of Arabidopsis thaliana lines overexpressing GLKs were compared with those in wild-type roots and leaves. Overexpression of GLKs caused up-regulation of not only their direct targets but also non-target nuclear and plastid genes, leading to global induction of chloroplast biogenesis in the root. Large antennae relative to reaction centers were observed in wild-type roots and were further enhanced by GLK overexpression due to the increased expression of target genes associated with peripheral light-harvesting antennae. Photochemical efficiency was lower in the root chloroplasts than in leaf chloroplasts, suggesting that the imbalance in the photosynthetic machinery decreases the efficiency of light utilization in root chloroplasts. Despite the low photochemical efficiency, root photosynthesis contributed to carbon assimilation in Arabidopsis. Moreover, GLK overexpression increased CO2 fixation and promoted phototrophic performance of the root, showing the potential of root photosynthesis to improve effective carbon utilization in plants.