Observations on the physiological mechanisms and chemical constituents of induced oleoresin synthesis in Pinusresinosa

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Abstract
The stimulation of lightwood formation (oleoresin soaking) in Pinusresinosa Ait. treated with the bipyridylium salt, paraquat (1,1′-dimethyl-4,4′-bipyridylium dichloride), affected various physiological parameters. Respiration, transpiration, and ethylene synthesis were markedly increased and were correlated with the increased production of rosin and turpentine. Photosynthesis, however, was severely inhibited, and phloem transport was not necessary for oleoresin deposition. These marked changes in function reflect a typical wounding response. Ethylene (supplied as Ethrel (2-chloroethylphosphonic acid)) was capable of replacing the stimulatory effect of paraquat, with a 14-fold increase in rosin over controls and a 25-fold increase in turpentine. This increase in turpentine content was accomplished by a significant enhancement in β-pinene content. Ethrel-treated trees also showed an increased abietic acid content, with a concomitant decrease in levopimaric acid.