摘要
Plants respond to low-nutrient conditions through metabolic and morphology changes that increase their ability to survive and grow. The transcription factor RAP2.11 was identified as a component in the response to low potassium through regulation of the high-affinity K＋ uptake transporter AtHAK5 and other components of the low- potassium signal transduction pathway. RAP2.11 was identified through the activation tagging of Arabidopsis lines that contained a luciferase marker driven by the AtHAK5 promoter that is normally only induced by low potassium. This factor bound to a GCC-box of the AtHAK5 promoter in vitro and in vivo. Transcript profiling revealed that a large number of genes were up-regulated in roots by RAP2.11 overexpression. Many regulated genes were identified to be in functional cate- gories that are important in Iow-K＋ signaling. These categories included ethylene signaling, reactive oxygen species pro- duction, and calcium signaling. Promoter regions of the up-regulated genes were enriched in the GCCGGC motif also contained in the AtHAK5 promoter. These results suggest that RAP2.11 regulates AtHAK5 expression under Iow-K＋ con- ditions and also contributes to a coordinated response to low-potassium conditions through the regulation of other genes in the Iow-K＋ signaling cascade.
Plants respond to low-nutrient conditions through metabolic and morphology changes that increase their ability to survive and grow. The transcription factor RAP2.11 was identified as a component in the response to low potassium through regulation of the high-affinity K＋ uptake transporter AtHAK5 and other components of the low- potassium signal transduction pathway. RAP2.11 was identified through the activation tagging of Arabidopsis lines that contained a luciferase marker driven by the AtHAK5 promoter that is normally only induced by low potassium. This factor bound to a GCC-box of the AtHAK5 promoter in vitro and in vivo. Transcript profiling revealed that a large number of genes were up-regulated in roots by RAP2.11 overexpression. Many regulated genes were identified to be in functional cate- gories that are important in Iow-K＋ signaling. These categories included ethylene signaling, reactive oxygen species pro- duction, and calcium signaling. Promoter regions of the up-regulated genes were enriched in the GCCGGC motif also contained in the AtHAK5 promoter. These results suggest that RAP2.11 regulates AtHAK5 expression under Iow-K＋ con- ditions and also contributes to a coordinated response to low-potassium conditions through the regulation of other genes in the Iow-K＋ signaling cascade.
