PLANT PHYSIOLOGY , Vol 109, Issue 1 53-61, Copyright © 1995 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Function of Phytochrome A in Potato Plants as Revealed through the Study of Transgenic Plants
A. G. Heyer, D. Mozley, V. Landschutze, B. Thomas and C. Gatz
Institut fur Genbiologische Forschung GmbH, Ihnestr. 63, 14195 Berlin, Germany (A.G.H., V.L.)
We have generated transgenic potato plants (Solanum tuberosum) containing
the potato phytochrome protein encoded by the PHYA gene cDNA (phyA) in
sense or antisense orientation under the control of the 35S cauliflower
mosaic virus promoter. Plants with increased and decreased phyA levels were
analyzed. When grown under white light, development and growth of sprouts
and plants were barely distinguishable from wild type. Under continuous
far-red light, stem extension, leaf expansion, and hook opening of sprouts
were accelerated in phyA overexpressors and delayed in antisense plants.
Sprouts with reduced phyA levels were less sensitive to red light with
regard to stem extension and expression of the small subunit genes for
ribulose bisphosphate carboxylase. Under low red light:far-red light
ratios, increased phyA levels reduced the stem extension component of the
shade-avoidance response, whereas decreased levels led to an increase in
the response.