THE IMPACT OF PLASTICITY AND MATERNAL EFFECT ON THE EVOLUTION OF LEAFRESIN PRODUCTION IN DIPLACUS-AURANTIACUS

Our previous quantitative genetic study of leaf resin production in Di placus aurantiacus revealed large environmental and maternal effects o n variation in resin production, which suggests the possibility of a g enotype x environment interaction for this trait when plants grow in h eterogeneous environments. Our objectives in this study were to observ e the genetic variation in plasticity of resin production under field and chamber conditions, compare phenotypic correlations of resin conte nt with growth traits under these two environmental conditions, and di stinguish the possible basis of the maternal effect on resin productio n using parents and half-sib progeny. A significant genotype x environ ment interaction (P < 0.0001) in leaf resin production was found, whic h suggests a potential for the evolution of plasticity of these second ary metabolites under heterogeneous environments. The phenotypic corre lation between resin content and growth rate also exhibited plasticity . In addition, the resin content of dam half-sib families grown in the chamber had a closer relationship with their maternal parents in the field (r = 0.65, P = 0.059) than in the chamber (r = 0.39, P = 0.34), suggesting an environmentally based maternal effect on the secondary c hemicals. We suggest that the maternal environmental effect may act as a contributor to plasticity of resin production and, while it may not diminish the appearance of the genotype x environment interaction, th e heritable variation of plasticity of resin production may be confoun ded.