Divergent geographic variation in above- versus belowground secondary metabolites of Reynoutria japonica
Data files
Dec 21, 2023 version files 25.53 KB
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knotweed2_f.csv
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README.md
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Abstract
- 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 well as between putative low-cost vs. high-cost compounds. While annual mean temperature was a stronger predictor of aboveground metabolites, annual precipitation was more frequently associated with variation in belowground metabolites. Moreover, annual temperature was positively associated with high-cost metabolites, but negatively with low-cost metabolites. Aboveground secondary metabolites were generally more strongly associated with functional traits (e.g., specific leaf area) than belowground metabolites, and in all cases, the directions of correlation were opposite for low-cost versus high-cost metabolites aboveground. The patterns of association also varied with latitude such that leaf concentrations of low-cost metabolites (quercetin) increased but those of high-cost metabolites (resveratrol, piceid and emodin) decreased at higher latitudes. In rhizomes, in contrast, the concentrations of high-cost metabolites (piceid and emodin) increased with latitude.
- Synthesis. Our findings indicate that allocation strategies differ between above- and belowground tissues of R. japonica. As latitude increases, R. japonica invests relatively more into belowground metabolites. We propose that reduced high-cost metabolites in the leaves at higher latitudes may help to conserve nutrients after defoliation, while maintaining high-cost metabolites in rhizomes may be important for persistent allelopathic effects and resource conservation belowground. The divergent patterns of above- and belowground metabolite allocation thus likely reflect the multiple functions of metabolites and the plants’ adaptation to different environments.
README: Divergent geographic variation in above- versus belowground secondary metabolites of Reynoutria japonica
https://doi.org/10.5061/dryad.3j9kd51rm
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
https://doi.org/10.5061/dryad.3j9kd51rm
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:
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.
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 mass spectrometry data for various samples, we integrated the chromatographic peaks of the different target compounds and conducted quantitative analysis using internal/external standards.
Plant Functional Traits: Recorded five key traits: measured the diameter (10 cm above the ground; mm) and number of branches of each selected R. japonica stem. We then collected five healthy leaves (the third to the eighth fully developed leaves from the top of each stem) to determine leaf toughness (N) with a SAUTER FA10 mechanical dynamometer, and to measure leaf chlorophyll content using a SPAD-502Plus chlorophyll meter. We also estimated leaf area using ImageJ on photos of these leaves and calculated specific leaf area (SLA; mm²/mg) as the leaf area divided by leaf dry mass.
Enemy Pressure: we primarily focused on chewing herbivores and pathogens. To quantify variation in leaf damage reflecting average natural herbivory, we collected four kinds of data using the selected five R. japonica stems at each site. Quantified herbivory and disease impact by (i) relative abundance of knotweed, (ii) percentage of leaves damaged by herbivores (Proportion_damaged; %), (iii) proportion of individuals with disease (LAL.TLA; %), and (iv) percentage of leaf area lost to herbivores (Pathogens), using ImageJ analysis of leaf photographs.
Environmental Variables: we measured soil pH using a 1:5 soil-water suspension (IQ Scientific Instruments, CA, USA). The soil samples were ground, sieved through a 2 mm mesh sieve, oven-dried at 60°C for 72 hr, weighed into tin capsules and measured for total carbon and nitrogen contents (S_TN, S_TC; mg/g) with an elemental analyzer (Vario MACRO cube, Elementar, Germany). Soil organic carbon content (SOC; mg/g) was measured based on the ignition loss method. In addition, we measured microbial biomass carbon (SMC; mg/kg) content using the chloroform fumigation-extraction method. We obtained climate data (BIO1/Annual Mean Temperature, C; BIO2/Mean Diurnal Range; BIO12/Annual Precipitation, mm; and solar_annual.mean, kJ/m2/d) for all study sites from http://worldclim.org/version2v.