Divergent geographic variation in above- versus belowground secondary metabolites of Reynoutria japonica

Secondary metabolites play an important role in plant adaptation because they can mitigate biotic and abiotic environmental stresses. However, their production and allocation incur different costs and benefits and are therefore subject to trade-offs, which are less studied.
To understand large-scale geographic patterns of secondary metabolites, and their environmental drivers and trade-offs, we studied 39 natural populations of the perennial herb Japanese knotweed (Reynoutria japonica) along a large latitudinal gradient in China. We measured the concentrations of six polyphenols in leaves and rhizomes of R. japonica and associated the variation in these metabolites with biotic and abiotic environmental factors as well as with functional plant traits and putative costs of secondary metabolites.
We found that climate was an important driver of variation in secondary metabolites, both above- and belowground. Remarkably, the patterns of association differed between leaves and rhizomes, as ..., , , # Divergent geographic variation in above- versus belowground secondary metabolites of *Reynoutria japonica*

Secondary metabolites, trait and environmental data for this study are available.

## Datasets included:

# Divergent geographic variation in above- versus belowground secondary metabolites of Reynoutria japonica

Secondary metabolites, trait and environmental data for this study are available.

We sampled R. japonica populations at 39 sites along a latitudinal gradient from 23.29°N to 31.40°N during peak growing season in July 2020.

## Datasets included:

1. Carbon and Nitrogen (TC, TN): Measured total carbon and nitrogen (mg/g) in leaf and rhizome samples using an elemental analyzer to calculate their C:N ratios.

2. Secondary Metabolites: Analyzed concentrations of six polyphenol metabolites (Quercetin, Ellagic acid, Piceid, Emodin and Catechin;μg/mL). We employed a triple quadrupole mass spectrometer with multiple reaction monitoring (MRM) capabilities. Upon obtaining m...