Programa de Pós-Graduação em Genética e Biologia Molecular Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Plant Cell Environ. 2013 Jan;36(1):52-67. doi: 10.1111/j.1365-3040.2012.02553.x. Epub 2012 Jul 4.
Among cereal crops, rice is considered the most tolerant to aluminium (Al). However, variability among rice genotypes leads to remarkable differences in the degree of Al tolerance for distinct cultivars. A number of studies have demonstrated that rice plants achieve Al tolerance through an unknown mechanism that is independent of root tip Al exclusion. We have analysed expression changes of the rice ASR gene family as a function of Al treatment. The gene ASR5 was differentially regulated in the Al-tolerant rice ssp. Japonica cv. Nipponbare. However, ASR5 expression did not respond to Al exposure in Indica cv. Taim rice roots, which are highly Al sensitive. Transgenic plants carrying RNAi constructs that targeted the ASR genes were obtained, and increased Al susceptibility was observed in T1 plants. Embryogenic calli of transgenic rice carrying an ASR5-green fluorescent protein fusion revealed that ASR5 was localized in both the nucleus and cytoplasm. Using a proteomic approach to compare non-transformed and ASR-RNAi plants, a total of 41 proteins with contrasting expression patterns were identified. We suggest that the ASR5 protein acts as a transcription factor to regulate the expression of different genes that collectively protect rice cells from Al-induced stress responses.
在谷类作物中，水稻被认为对铝（Al）最具耐受性。然而，水稻基因型的变异性导致不同品种对铝耐受性的程度存在显著差异。许多研究表明，水稻植物通过一种未知的机制实现了铝耐受性，该机制与根尖铝排斥无关。我们分析了水稻 ASR 基因家族的表达变化作为铝处理的功能。基因 ASR5 在耐铝水稻亚种粳稻 cv. Nipponbare 中受到差异调控。然而，在铝敏感的籼稻 cv. Taim 根中，ASR5 的表达并不响应铝暴露。获得了携带针对 ASR 基因的 RNAi 构建体的转基因植物，并且在 T1 植物中观察到增加的铝敏感性。携带 ASR5-绿色荧光蛋白融合的转基因水稻胚性愈伤组织表明，ASR5 定位于细胞核和细胞质中。使用蛋白质组学方法比较非转化和 ASR-RNAi 植物，共鉴定出 41 种表达模式相反的蛋白质。我们认为 ASR5 蛋白作为转录因子发挥作用，调节不同基因的表达，这些基因共同保护水稻细胞免受铝诱导的应激反应。
