Disruption of the psbA gene by the copy correction mechanism reveals that the expression of plastid-encoded genes is regulated by photosynthesis activity
Disruption of the psbA gene by the copy correction mechanism reveals that the expression of plastid-encoded genes is regulated by photosynthesis activity
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DOI：
10.1007/s10265-007-0082-3
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发表时间：
2007-04
影响因子：
2.8
通讯作者：
M. S. Khan;Waqar Hameed;Mikio Nozoe;T. Shiina
中科院分区：
文献类型：
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作者：
M. S. Khan;Waqar Hameed;Mikio Nozoe;T. Shiina
利用反向遗传学对烟草叶绿体基因组编码的基因进行功能分析是常规的。然而，对于少数基因，它们的缺失产生异质基因型，使它们的分析复杂化。因此，需要额外的策略来开发这些基因的缺失突变体。我们已经开发了一种基于同源拷贝校正的策略，用于删除/突变叶绿体基因组上编码的基因。该系统用于产生epsbA敲除。所得到的植物是同质的并且缺乏光系统II（PSII）活性。此外，缺失突变体表现出不同的表型;幼叶是绿色的，而老叶是漂白的，与光照条件无关。这表明psbA的缺乏促进了衰老。转录水平的分析表明，NEP（核编码的质体RNA聚合酶）依赖的质体基因的上调在thepsbA缺失突变体，而漂白叶保留质体编码的质体RNA聚合酶活性。因此，NEP依赖的质体基因的表达可能直接或间接地受到光合作用的调节。
The functional analysis of genes encoded by the chloroplast genome of tobacco by reverse genetics is routine. Nevertheless, for a small number of genes their deletion generates heteroplasmic genotypes, complicating their analysis. There is thus the need for additional strategies to develop deletion mutants for these genes. We have developed a homologous copy correction-based strategy for deleting/mutating genes encoded on the chloroplast genome. This system was used to producepsbAknockouts. The resulting plants are homoplasmic and lack photosystem II (PSII) activity. Further, the deletion mutants exhibit a distinct phenotype; young leaves are green, whereas older leaves are bleached, irrespective of light conditions. This suggests that senescence is promoted by the absence ofpsbA. Analysis of the transcript levels indicates that NEP (nuclear-encoded plastid RNA polymerase)-dependent plastid genes are up regulated in thepsbAdeletion mutants, whereas the bleached leaves retain plastid-encoded plastid RNA polymerase activity. Hence, the expression of NEP-dependent plastid genes may be regulated by photosynthesis, either directly or indirectly.