PNNL

Abstract

The metabolome, the chemical phenotype of an organism, should be shaped by evolution. Metabolomes depend on genetic composition and expression, which can be sources of evolutionary inertia, so most aspects of metabolomes should be similar in closely related sympatric species. We examined the metabolomes of two sympatric subspecies of Pinus sylvestris in Sierra Nevada (southern Iberian Peninsula), one introduced (ssp. iberica) and one autochthonous (ssp. nevadensis), in summer and winter and exposed to folivory by the pine processionary moth. The overall metabolomes differed between the subspecies but both tended to respond more similarly to folivory. The metabolomes of the subspecies were more dissimilar in summer than in winter, and iberica trees had higher concentrations of metabolites directly related to drought stress. Our results suggest that certain plant metabolic responses associated with folivory have been conserved throughout evolutionary history. The larger divergence between subspecies metabolomes in summer is likely due to the warmer and drier conditions that the northern iberica subspecies experience in Sierra Nevada. Our results provide crucial insights into how iberica populations would respond to the predicted conditions of climate change under an increased defoliation, two recent severe issues in the Mediterranean Basin.