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  3. 2016

Enhancement of ozone resistance by adjusting the stomatal aperture on leaf surface

Description

Tropospheric ozone (O3) is a major photochemical oxidant and one of the most phytotoxic air pollutants. Ozone levels have been increasing in many parts of the world, with high concentrations of ozone causing serious damage to crop production. Because ozone enters the plant through the stomata, modulation of stomatal movement using transcription factors, which act as master regulators of various cellular processes, may be a useful strategy for conferring ozone resistance. However, transcription factors modulating stomatal movement have not been well characterized.

In this report, we screened a set of transgenic Arabidopsis lines expressing chimeric repressors for Arabidopsis transcription factors to identify new transcription factors related with ozone stress resistance. We found that lines expressing the chimeric repressors for GOLDEN 2-LIKE1 (GLK1) and GLK2, which have known functions in chloroplast development, exhibit remarkable ozone resistance and a closed-stomata phenotype. In addition to ozone resistance, these plants also exhibited resistance to sulfur dioxide, an oxidative stress reagent similar to ozone. On the other hand, plants that overexpress GLK1/2 exhibited higher sensitivity to ozone and sulfur dioxide, and an open-stomata phenotype. These results suggest that GLK1/2 affect ozone and sulfur dioxide resistance through the regulation of stomatal movement. We showed that lines expressing the chimeric repressors for GLK1 had reduced expression of the genes for inwardly rectifying K+ (K+in) channels and reduced K+in channel activity, which is one of the positive regulators for stomatal opening. These results indicate that GLK1/2 act as positive regulators of genes for K+in channels and stomatal opening.

Stomata play roles in the transpiration and absorption of gases in plants. Thus, the modification of stomatal movements could prove useful for improving both the efficiency of photosynthesis and the plants’ resistance to air pollutants. Regulating the expression of chimeric repressors for GLK1/2 specifically in guard cells may be a useful tool for conferring resistance to air pollutants.

Figure, table

  1. Fig. 1. Sensitivity to ozone of GLK1/2-downregulated Arabidopsis.

    Fig. 1. Sensitivity to ozone of GLK1/2-downregulated Arabidopsis.
    A. Two-week-old plants of wild type and GLK1/2-downregulated Arabidopsis (GLK1sx andGLK2sx) 1d after exposure to 0.3 ppm ozone for 7h.
    B. Ion leakage of wild type and GLK1/2sx plants. The average of three biological replicates (three plants per replicate) is shown. Error bars represent SD.

  2. Fig. 2. Transpiration and stomatal aperture of GLK1/2-downregulated Arabidopsis.

    Fig. 2. Transpiration and stomatal aperture of GLK1/2-downregulated Arabidopsis.
    A. Thermal images of wild type and GLK1sx plants grown on MS medium, showing the higher temperature of GLK1sx plants.
    B. Stomatal aperture of wild type and GLK1sx plants grown on MS medium. The average of three independent experiments is shown (50 stomata per experiment).
    Error bars represent SD.

Affiliation

Japan International Research Center for Agricultural Sciences Biological Resources and Post-harvest Division

Research project
Program name

Stable Agricultural Production

Term of research

FY2016（FY2015～FY2016）

Responsible researcher

Nagatoshi Yukari ( Biological Resources and Post-harvest Division )

MIERUKA ID: 001763

Mitsuda Nobutaka ( National Institute of Advanced Industrial Science and Technology )

Kubo Akihiro ( National Institute for Environmental Studies )

Saji Hiraru ( National Institute for Environmental Studies )

KAKEN Researcher No.: 00178683

Hayashi Maki ( Nagoya University )

Inoue Shin-ichiro ( Nagoya University )

KAKEN Researcher No.: 40532693

Kinoshita Toshinori ( Nagoya University )

KAKEN Researcher No.: 50271101

Okuma Eiji ( Okayama University )

Murata Yoshiyuki ( Okayama University )

KAKEN Researcher No.: 70263621

Seo Mitsunori ( RIKEN )

KAKEN Researcher No.: 00512435

Takagi Masaru ( Saitama University )

KAKEN Researcher No.: 40357348

ほか
Publication, etc.

Nagatoshi Y et al. (2016) Proc Natl Acad Sci USA, 113:4218-4223

https://doi.org/10.1073/pnas.1513093113

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