Nitrate Transport and Not Photoinhibition Limits Growth of the Freshwater Cyanobacterium <i>Synechococcus</i> Species PCC 6301 at Low Temperature1

  • Toshio Sakamoto
    Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
  • Donald A. Bryant
    Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802

抄録

<jats:title>Abstract</jats:title> <jats:p>The effect of low temperature on cell growth, photosynthesis, photoinhibition, and nitrate assimilation was examined in the cyanobacterium Synechococcus sp. PCC 6301 to determine the factor that limits growth.Synechococcus sp. PCC 6301 grew exponentially between 20°C and 38°C, the growth rate decreased with decreasing temperature, and growth ceased at 15°C. The rate of photosynthetic oxygen evolution decreased more slowly with temperature than the growth rate, and more than 20% of the activity at 38°C remained at 15°C. Oxygen evolution was rapidly inactivated at high light intensity (3 mE m−2 s−1) at 15°C. Little or no loss of oxygen evolution was observed under the normal light intensity (250 μE m−2 s−1) for growth at 15°C. The decrease in the rate of nitrate consumption by cells as a function of temperature was similar to the decrease in the growth rate. Cells could not actively take up nitrate or nitrite at 15°C, although nitrate reductase and nitrite reductase were still active. These data demonstrate that growth at low temperature is not limited by a decrease in the rate of photosynthetic electron transport or by photoinhibition, but that inactivation of the nitrate/nitrite transporter limits growth at low temperature.</jats:p>

収録刊行物

  • Plant Physiology

    Plant Physiology 119 (2), 785-794, 1999-02-01

    Oxford University Press (OUP)

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