Phosphatidylglycerol (PG) is the only major phospholipid in the thylakoid membrane of chloroplasts. PG is essential for photosynthesis and loss of PG in Arabidopsis thaliana results in severe defects of growth and chloroplast development with decreased chlorophyll accumulation, impaired thylakoid formation, and downregulation of photosynthesis-associated genes encoded in nuclear and plastid genomes. However, how the absence of PG affects the gene expression and plant growth remains unclear. To elucidate this mechanism, we investigated the growth and transcriptional profiles of a PG-deficient Arabidopsis mutant pgp1-2 under various light conditions. Microarray analysis demonstrated that reactive oxygen species-responsive genes were upregulated in pgp1-2. Decreased growth light did not alleviated the impaired leaf development and the downregulation of photosynthesis-associated genes in pgp1-2, indicating limited impacts of photooxidative stress on the defects of pgp1-2. Illumination to dark-adapted pgp1-2 triggered downregulation of photosynthesis-associated nuclear-encoded genes (PhANGs), while plastid-encoded genes were constantly suppressed. Overexpression of GOLDEN2-LIKE1 (GLK1), a transcription factor regulating chloroplast development, in pgp1-2 upregulated PhANGs but not plastid-encoded genes along with chlorophyll accumulation. Our data suggest a broad impact of PG biosynthesis on nuclear-encoded genes partially via GLK1 and a specific involvement of this lipid in the plastid gene expression and plant development.

中文翻译：

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磷脂酰甘油合成促进质体基因表达和核光合基因的光诱导

磷脂酰甘油 (PG) 是叶绿体类囊体膜中唯一的主要磷脂。PG 对光合作用至关重要，拟南芥中PG 的缺失导致生长和叶绿体发育严重缺陷，叶绿素积累减少、类囊体形成受损，以及核和质体基因组中编码的光合作用相关基因下调。然而，PG的缺失如何影响基因表达和植物生长仍不清楚。为了阐明这种机制，我们研究了缺乏 PG 的拟南芥突变体pgp1-2在各种光照条件下的生长和转录谱。微阵列分析表明活性氧响应基因在pgp1-2中上调. 生长光的减少并没有减轻叶片发育受损和pgp1-2中光合作用相关基因的下调，表明光氧化应激对pgp1-2缺陷的影响有限。对暗适应pgp1-2 的光照触发了光合作用相关核编码基因 (PhANGs) 的下调，而质体编码基因则不断受到抑制。的过表达GOLDEN2-LIKE1（GLK1），转录因子调节叶绿体发育，在pgp1-2上调 PhANGs 但不上调质体编码基因以及叶绿素积累。我们的数据表明 PG 生物合成对核编码基因的广泛影响部分通过 GLK1 以及这种脂质在质体基因表达和植物发育中的特定参与。