LIGHT REQUIREMENTS FOR THE ENHANCED SYNTHESIS OF A PLASTID mRNA DURING SPIRODELA GREENING |
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Authors: | Jonathan Gressel |
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Institution: | Department of Plant Genetics, The Weizmann Institute of Science, Rehovot, Israel |
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Abstract: | A plastid mRNA (5 × 105 mol wt) appears as a burst 3 h after white light greening of steady state dark grown plants of Spirodela oligorrhiza. In this species, chlorophyll synthesis begins after 12 h. The light requirement is different from the pulse of far-red reversible red light required to abolish the lag of chlorophyll synthesis in many species, including Spirodela. Continuous high energy far-red is not stimulatory. When the illumination is not continued throughout the time of incorporation, the stimulation is minimal. Low energy blue and red light are stimulatory, and green and far-red light are ineffectual. Blue light was > 5 times as effective as red light at many dose levels. Illumination with 3 × 1017 quanta/m2/s (50pEm/cm2/s) blue light at 476 nm gave about half maximum stimulation. |
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