PLANT PHYSIOLOGY , Vol 105, Issue 4 1059-1066, Copyright © 1994 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Ultraviolet-B-Responsive Anthocyanin Production in a Rice Cultivar Is Associated with a Specific Phase of Phenylalanine Ammonia Lyase Biosynthesis
V. S. Reddy, K. V. Goud, R. Sharma and A. R. Reddy
School of Life Sciences, University of Hyderabad, Hyderabad-500134, India
Seedlings of 17 rice (Oryza sativa L.) cultivars were classified on the
basis of anthocyanin pigmentation into three groups: an acyanic group with
9 cultivars, a moderately cyanic group with 5 cultivars, and a cyanic group
with 3 cultivars. Seedlings of the cyanic group were deep purple in color,
possessing copious amounts of anthocyanin in shoots. Sunlight (SL)-mediated
anthocyanin and phenylalanine ammonia lyase (PAL) induction in a cyanic
cultivar, purple puttu, was compared with an acyanic cultivar, black puttu.
A brief exposure of dark-grown purple puttu seedlings to SL induced
anthocyanin formation during a subsequent dark period with a peak at 24 h.
The magnitude of SL-mediated anthocyanin induction is age dependent, the
4-d-old seedlings being the most responsive to SL. The anthocyanin
induction in purple puttu seedlings is mediated exclusively by the
ultraviolet-B (UV-B) component of SL. The SL-triggered anthocyanin
induction was reduced by about 30% by a terminal far-red light pulse and
was restored by a red light pulse, indicating the role of phytochrome in
modulation of anthocyanin level. The SL-mediated induction of PAL showed
two peaks, one at 4 h and the other at 12 h. Whereas the first PAL peak (4
h) was induced by phytochrome and was seen in both cultivars, the second
PAL peak (12 h) was inducible by UV-B only in the cyanic purple puttu
cultivar.