期刊
PLANT JOURNAL
卷 72, 期 5, 页码 732-744出版社
WILEY
DOI: 10.1111/j.1365-313X.2012.05106.x
关键词
inorganic phosphate; Golgi apparatus; vacuole; phosphate compartmentation; mimic disease; Arabidopsis
资金
- Deutsche Forschungsgemeinschaft [FOR 1061]
- Deutsche Forschungsgemeinschaft
The Golgi-located phosphate exporter PHT4;6 has been described as involved in salt tolerance but further analysis on the physiological impact of PHT4;6 remained elusive. Here we show that PHT4;6GFP is targeted to the trans-Golgi compartment and that loss of function of this carrier protein has a dramatic impact on plant growth and development. Knockout mutants of pht4;6 exhibit a dwarf phenotype that is complemented by the homologous gene from rice (Oryza sativa). Interestingly, pht4;6 mutants show altered characteristics of several Golgi-related functions, such as an altered abundance of certain N-glycosylated proteins, altered composition of cell-wall hemicelluose, and higher sensitivity to the Golgi a-mannosidase and the retrograde transport inhibitors kifunensine and brefeldin A, respectively. Moreover, pht4;6 mutants exhibit a mimic disease phenotype accompanied by constitutively activated pathogen defense mechanisms and increased resistance against the virulent Pseudomonas syringae strain DC3000. Surprisingly, pht4;6 mutants also exhibit phosphate starvation symptoms, as revealed at the morphological and molecular level, although total Pi levels in wild-type and pht4;6 plants are similar. This suggested that subcellular Pi compartmentation was impaired. By use of nuclear magnetic resonance (NMR), increased Pi concentration was detected in acidic compartments of pht4;6 mutants. We propose that impaired Pi efflux from the trans-Golgi lumen results in accumulation of inorganic phosphate in other internal compartments, leading to low cytoplasmic phosphate levels with detrimental effects on plant performance.
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