Journal Article

Regulatory Mechanisms of ROI Generation are Affected by Rice <i>spl</i> Mutations

Kaori Kojo, Takashi Yaeno, Kensuke Kusumi, Hideo Matsumura, Shizuko Fujisawa, Ryohei Terauchi and Koh Iba

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 8, pages 1035-1044
Published in print August 2006 | ISSN: 0032-0781
Published online August 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcj074
Regulatory Mechanisms of ROI Generation are Affected by Rice spl Mutations

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Reactive oxygen intermediates (ROIs) play a pivotal role in the hypersensitive response (HR) in disease resistance. NADPH oxidase is a major source of ROI; however, the mechanisms of its regulation are unclear. Rice spl mutants spontaneously form lesions which resemble those occurring during the HR, suggesting that the mutations affect regulation of the HR. We found that spl2, spl7 and spl11 mutant cells accumulated increased amounts of H2O2 in response to rice blast fungal elicitor. Increased accumulation of ROIs was suppressed by inhibition of NADPH oxidase in the spl cells, and was also observed in the ozone-exposed spl plants. These mutants have sufficient activities of ROI-scavenging enzymes compared with the wild type. In addition, spl7 mutant cells accumulated higher amounts of H2O2 when treated with calyculin A (CA), an inhibitor of protein phosphatase. Furthermore, spl2 mutant plants exhibited accelerated accumulation of H2O2 and increased rates of cell death in response to wounding. These results suggest that the spl2, spl7 and spl11 mutants are defective in the regulation of NADPH oxidase, and the spl7 mutation may give rise to enhancement of the signaling pathway which protein dephosphorylation controls, while the spl2 mutation affects both the pathogen-induced and wound-induced signaling pathways.

Keywords: Lesion mimic; NADPH oxidase; spl

Journal Article.  5657 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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