<b>Reduced phenolic oxidation at culture initiation<i>in vitro</i>following the exposure of field-grown stockplants to darkness or low levels of irradiance</b>

Abstract

AbstractPhenolic oxidation causing loss of explants was minimized or eliminated when cultures were initiated in vitro from either dark-grown field stockplants, or those exposed to 1% irradiance. Hamamelis mollis ‘Pallida’, Garrya elliptica ‘James Roof and Acer platanoides ‘Crimson King’ were more responsive than Quercus robur ‘Fastigiata’. With the exception of the last, all surviving explants continued to grow without further appearance of oxidation products. Phenolic oxidation was not prevented by culturing explants in darkness during the initial phase in vitro, but this enhanced the suppression already initiated by reduced irradiance in the field for Hamamelis and Garrya. The inclusion in vitro of activated charcoal was detrimental to the viability and growth of the Acer explants, with which it was tested, irrespective of earlier field treatments. The likelihood that these effects were mediated through the limitation of light-induced events in phenolic metabolism are discussed.