Li Yunhai, Smith Caroline, Corke Fiona, Zheng Leiying, Merali Zara, Ryden Peter, Derbyshire Paul, Waldron Keith, Bevan Michael W
Department of Cell and Developmental Biology, John Ines Centre, Norwich NR4 7UH, United Kingdom.
Plant Cell. 2007 Aug;19(8):2500-15. doi: 10.1105/tpc.106.049965. Epub 2007 Aug 10.
Sugars such as glucose function as signal molecules that regulate gene expression, growth, and development in plants, animals, and yeast. To understand the molecular mechanisms of sugar responses, we isolated and characterized an Arabidopsis thaliana mutant, high sugar response8 (hsr8), which enhances sugar-responsive growth and gene expression. Light-grown hsr8 plants exhibited increased starch and anthocyanin and reduced chlorophyll content in response to glucose treatment. Dark-grown hsr8 seedlings showed glucose-hypersensitive hypocotyl elongation and development. The HSR8 gene, isolated using map-based cloning, was allelic to the MURUS4 (MUR4) gene involved in arabinose synthesis. Dark-grown mur1 and mur3 seedlings also exhibited similar sugar responses to hsr8/mur4. The sugar-hypersensitive phenotypes of hsr8/mur4, mur1, and mur3 were rescued by boric acid, suggesting that alterations in the cell wall cause hypersensitive sugar-responsive phenotypes. Genetic analysis showed that sugar-hypersensitive responses in hsr8 mutants were suppressed by pleiotropic regulatory locus1 (prl1), indicating that nucleus-localized PRL1 is required for enhanced sugar responses in hsr8 mutant plants. Microarray analysis revealed that the expression of many cell wall-related and sugar-responsive genes was altered in mur4-1, and the expression of a significant proportion of these genes was restored to wild-type levels in the mur4-1 prl1 double mutant. These findings reveal a pathway that signals changes in the cell wall through PRL1 to altered gene expression and sugar-responsive metabolic, growth, and developmental changes.
葡萄糖等糖类作为信号分子,在植物、动物和酵母中调节基因表达、生长和发育。为了解糖响应的分子机制,我们分离并鉴定了拟南芥突变体高糖响应8(hsr8),该突变体增强了糖响应性生长和基因表达。光照下生长的hsr8植株在葡萄糖处理后表现出淀粉和花青素含量增加,叶绿素含量降低。黑暗中生长的hsr8幼苗表现出对葡萄糖超敏感的下胚轴伸长和发育。通过图位克隆分离出的HSR8基因与参与阿拉伯糖合成的MURUS4(MUR4)基因等位。黑暗中生长的mur1和mur3幼苗对hsr8/mur4也表现出类似的糖响应。硼酸挽救了hsr8/mur4、mur1和mur3的糖超敏感表型,表明细胞壁的改变导致超敏感的糖响应表型。遗传分析表明多效调控位点1(prl1)抑制了hsr8突变体中的糖超敏感反应,这表明细胞核定位的PRL1是hsr8突变体植株增强糖响应所必需的。微阵列分析显示,mur4-1中许多细胞壁相关和糖响应基因的表达发生了改变,在mur4-1 prl1双突变体中,这些基因中有很大一部分的表达恢复到了野生型水平。这些发现揭示了一条通过PRL1将细胞壁变化信号传递到基因表达改变以及糖响应性代谢、生长和发育变化的途径。