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|標題:||AtRBOH I confers submergence tolerance and is involved in auxin-mediated signaling pathways under hypoxic stress|
Jason T. C. Tzen
|摘要:||Plants suffer from oxygen deficiency (hypoxia) and energy starvation under flooding conditions. Higher plants have evolved complex adaptive mechanisms to flooding that are induced by changes in the cellular redox state and phytohormones. Previously, we showed that the transcript levels of respiratory burst oxidase homolog I (AtRBOH I) in Arabidopsis increase under hypoxic stress. In this study, we used two independent Atrboh I-knockout lines to assess the molecular function of AtRBOH I in hypoxic signaling pathways. Under submergence conditions, the Atrboh I-knockout lines had a reduced survival rate and lower chlorophyll contents than those of wild type. The patterns of AtRBOH I expression were analyzed by fusing its promoter to the GUS reporter. These expression analyses indicated that AtRBOH I expression was activated by hypoxia, but this induction was reduced by the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Quantitative RT-PCR analyses showed that the transcript levels of hypoxia-inducible genes (AtHRE1, AtADH1, AtLDH, and AtSUS1) were reduced in AtRBOH I-knockout lines under hypoxic conditions. The transcript levels of AtSUS1 were lower in AtRBOH I-knockout lines than in wild type in the hypoxia combined with NPA treatment. Hypoxic conditions increased the transcript levels of the auxin-responsive genes At1g19840, At3g23030, and At5g19140, and hypoxia combined with NPA resulted in increased transcript levels of the ethylene biosynthetic genes AtACS7 and AtACS8. Together, these results show that AtRBOH I regulates the expression of genes involved in ethylene biosynthesis and down-stream of hypoxia signaling, and that there is some interplay between hypoxia signaling and auxin-mediated signaling pathways under hypoxic stress.|
|Appears in Collections:||農藝學系|
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