The mutant allele of rice calmodulin-binding transcription activator OsCBT, oscbt-1, exhibits broad-spectrum resistance against rice pathogens. Previously, we reported that the strong resistance of the oscbt-1 mutant to pathogens was conferred by a constitutive upregulation of defense-related genes even under pathogen-free conditions. We also found strong induction of the hypersensitive response as a reaction to pathogen invasion. The results suggest that OsCBT acts as a negative regulator of basal resistance to pathogen attack. To identify the transcriptional network regulated by OsCBT, we compared global gene expression profiles between wild-type (WT) and oscbt-1 rice plants grown under pathogen-free conditions. The results of a 3′ tiling microarray revealed that in oscbt-1 plants, 81 genes are upregulated and 200 genes are downregulated when compared with the WT. A gene ontology analysis showed that differentially regulated genes in oscbt-1 were very closely associated with “death” GO term in a biological process category, and “catalytic activity” and “binding” GO terms in a molecular function category. A MapMan analysis indicated that the functions of these genes were associated with plant responses to biotic stress. Moreover, the results from quantitative real-time PCR in the oscbt-1 mutant showed a significant effect on the gene expression patterns of the fungal pathogen response. Our results suggested that the OsCBT regulates a rice defense response by modulating the expressions of various defense-related genes.

中文翻译：

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水稻CaM结合转录因子（OsCBT）通过转录重编程介导防御信号

水稻钙调蛋白结合转录激活因子OsCBT oscbt-1的突变等位基因显示出对水稻病原体的广谱抗性。以前，我们报道了即使在无病原体条件下，防御相关基因的组成型上调也赋予了oscbt-1突变体对病原体的强抗性。我们还发现超敏反应强烈诱导为对病原体入侵的反应。结果表明，OsCBT作为基础抵抗病原体攻击的负调节器。为了确定由OsCBT调控的转录网络，我们比较了野生型（WT）和oscbt-1之间的全局基因表达谱在无病原体条件下生长的水稻植株。3'平铺微阵列的结果表明，与WT相比，在oscbt-1植物中有81个基因被上调，而200个基因被下调。基因本体分析表明，oscbt-1中差异调节的基因与生物学过程类别中的“死亡” GO术语以及分子功能类别中的“催化活性”和“结合” GO术语密切相关。MapMan分析表明，这些基因的功能与植物对生物胁迫的反应有关。此外，oscbt-1中定量实时PCR的结果突变体显示出对真菌病原体反应的基因表达模式的显着影响。我们的结果表明，OsCBT通过调节各种防御相关基因的表达来调节水稻的防御反应。