Kalancho? PPC1 is Essential for Crassulacean Acid Metabolism and the Regulation of Core Circadian Clock and Guard Cell Signaling Genes

编号 040023102

推送时间 20200323

研究领域 森林培育 

年份 2020 

类型 期刊 

语种 英语

标题 Kalancho? PPC1 is Essential for Crassulacean Acid Metabolism and the Regulation of Core Circadian Clock and Guard Cell Signaling Genes

来源期刊 The Plant Cell

期 第231期

发表时间 20200212

关键词 Crassulacean acid metabolism (CAM) plants;  oxaloacetate;  phosphoenolpyruvate carboxylase;  circadian clock; 

摘要 Unlike C3 plants, Crassulacean acid metabolism (CAM) plants fix CO2 in the dark using phosphoenolpyruvate carboxylase (PPC; EC 4.1.1.31). PPC combines PEP with CO2 (as HCO3-), forming oxaloacetate that is converted to malate, leading to vacuolar malic acid accumulation that peaks phased to dawn. In the light period, malate decarboxylation concentrates CO2 around RuBisCO for secondary fixation. CAM mutants lacking PPC have not been described. Here, RNAi was employed to silence CAM isogene PPC1 in Kalancho? laxiflora. Line rPPC1-B lacked PPC1 transcripts, PPC activity, dark period CO2 fixation, and nocturnal malate accumulation. Light period stomatal closure was also perturbed, and the plants displayed reduced but detectable dark period stomatal conductance, and arrhythmia of the CAM CO2 fixation circadian rhythm under constant light and temperature (LL) free-running conditions. By contrast, the rhythm of delayed fluorescence was enhanced in plants lacking PPC1. Furthermore, a subset of gene transcripts within the central circadian oscillator were up-regulated and oscillated robustly. The regulation of guard cell genes involved in controlling stomatal movements was also perturbed in rPPC1-B. This provided direct evidence that the regulatory patterns of key guard cell signaling genes are linked with the characteristic inverse pattern of stomatal opening and closing during CAM.

服务人员 孙小满

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