Influence of phytochrome on leaf monoterpene variation in Satureja douglasii

Phytochrome influenced monoterpene variation in mature leaves of Satureja douglasii in a chemotype-dependent manner. Phytochrome significantly increased the concentrations (mg g(-1) leaf dry weight) of camphor, pulegone and carvone and the yield (total amount mg g(-1) leaf dry weight) in the pulegone and carvone chemotypes. However, phytochrome did not influence monoterpene concentrations nor yield in the bicyclic or isomenthone chemotypes. The phytochrome action in the pulegone type is a low fluence response, whereas in the carvone type it is both a low and a very low fluence response. However, statistically, the composition (percent of total monoterpenes) that defines the chemotypes was not significantly influenced by phytochrome and supports other studies suggesting genetic control of the chemotype composition. The chemotypes tend to occur in a particular light environment, although one occurs across a wide range of them. The chemotype-dependent phytochrome response for monoterpene variation may result from adaptation to the light environments where the chemotypes usually occur. (C) 1998 Elsevier Science Ltd. All rights reserved.