Kumari Manjeet, Taylor Gregory J, Deyholos Michael K
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Mol Genet Genomics. 2008 Apr;279(4):339-57. doi: 10.1007/s00438-007-0316-z. Epub 2008 Feb 13.
To help characterize the cellular mechanisms underlying the toxicity of Al to plants, we present the first large-scale, transcriptomic analysis of root responses to Al, using a microarray representing approximately 93% of the predicted genes in the genome of Arabidopsis. More transcripts were responsive to Al (25 microM) during long (48 h, 1,114 genes), as compared to short (6 h, 401 genes) exposures, which contrasts with previous microarray analyses of plant responses to other types of abiotic stress. Exposure to Al triggered changes in the transcript levels for several genes related to oxidative stress pathway, membrane transporters, cell wall, energy, and polysaccharide metabolism. Interestingly, lack of abundance of transcripts encoding TCA cycle enzymes, except for malate dehydrogenase, suggested that synthesis of organic anions in response to Al may not be transcriptionally regulated. Al exposures induced differential abundance of transcripts for several ribosomal proteins, peptidases and protein phosphatases mostly after 48 h. We also detected increased abundance of transcripts for several membrane receptor kinases and non-membrane calcium response kinases, which could play a role in transmission of Al-stress signals. Among Al responsive transcription factors, the most predominant families identified were AP2/EREBP, MYB and bHLH. Further, we studied the kinetics of Al stress responses for class III peroxidases using Q-RT-PCR. Our results indicated that Al triggered dynamic changes in transcript abundance of various peroxidases within 1 h. The results of this screen contribute to the identification of candidate genes for the generation of Al-tolerant transgenic plants.
为了帮助阐明铝对植物毒性的细胞机制，我们利用一个代表拟南芥基因组中约93%预测基因的微阵列，首次对根对铝的反应进行了大规模转录组分析。与短时间（6小时，401个基因）暴露相比，长时间（48小时，1114个基因）暴露于铝（25微摩尔）时，更多的转录本对铝有反应，这与之前对植物对其他类型非生物胁迫反应的微阵列分析形成对比。暴露于铝会引发与氧化应激途径、膜转运蛋白、细胞壁、能量和多糖代谢相关的几个基因转录水平的变化。有趣的是，除了苹果酸脱氢酶外，编码三羧酸循环酶的转录本丰度较低，这表明响应铝的有机阴离子合成可能不受转录调控。铝暴露主要在48小时后诱导了几种核糖体蛋白、肽酶和蛋白磷酸酶转录本的差异丰度。我们还检测到几种膜受体激酶和非膜钙反应激酶的转录本丰度增加，它们可能在铝胁迫信号的传递中起作用。在对铝有反应的转录因子中，最主要的家族是AP2/EREBP、MYB和bHLH。此外，我们使用定量逆转录聚合酶链反应研究了III类过氧化物酶对铝胁迫反应的动力学。我们的结果表明，铝在1小时内引发了各种过氧化物酶转录本丰度的动态变化。该筛选结果有助于鉴定耐铝转基因植物的候选基因。
