J. Peñuelas (CREAF)

Long-term fertilization determines different metabolomic profiles and responses in saplings of three rainforest tree species with different adult canopy position

We studied the foliar metabolome of saplings of three abundant tree species in a 15 year field NPK fertilization experiment in a Panamanian rainforest. The largest differences were among species and explained 75% of overall metabolome variation. The saplings of the large canopy species, Tetragastris panamensis , had the lowest concentrations of all identi- fied amino acids and the highest concentratio ns of most identified secondary compounds. The saplings of the “ mid canopy” species, Alseis blackiana , had the highest concentratio ns of amino acids coming from the biosynthesis pathways of glycerate-3P, oxaloacetate and α - ketoglutarate, and the saplings of the low canopy species, Heisteria concinna , had the high- est concentratio ns of amino acids coming from the pyruvate synthesis pathways.

Ecometabolomics: Optimized NMR-based procedures

Here we propose a NMR‐based protocol for ecometabolomic studies that provides an unbiased overview of the metabolome of an organism, including polar and nonpolar metabolites. This protocol is aimed to facilitate the analysis of many samples, as typically required in ecological studies. In addition to NMR fingerprinting, it identifies metabolites for generating metabolic profiles applying strategies of elucidation of small molecules typically used in natural‐product research, and allowing the identification of secondary and unknown metabolites. We also provide a detailed description to obtain the numerical data from the ¹H‐NMR spectra needed to perform the statistical analyses.

Opposite metabolic responses of shoots and roots to drought

Shoots and roots have different metabolomes and nutrient and elemental stoichiometries, the shoot metabolome is much more variable among species and seasons than is the root metabolome and the metabolic response of shoots to drought contrasts with that of roots; shoots decrease their growth metabolism (lower concentrations of sugars, amino acids, nucleosides, N, P, and K), and roots increase it in a mirrored response.

Drought enhances folivory by shifting foliar metabolomes in Quercus ilex trees

The present study is an example of how coupling stoichiometric with metabolomic techniques is useful for identifying the molecular responses of plants to changing environmental conditions such as drought, for understanding the mechanisms and functions that underlie the responses of plants to these new conditions and for interpreting the implications of drought for trophic webs. Foliar N : P ratios of Q. ilex did not significantly change between seasons and were not lowest in spring, the growing season, as expected from the growth rate hypothesis. Foliar K concentrations, however, did change, demonstrating the importance of K in natural summer droughts. The lack of significant variation in N and P concentrations in Q. ilex may be attributable to the buffering effect of lignotubers in this woody species. Moderate experimental drought increased the concentrations of sugars and polyphenolic compounds with antioxidant function in the leaves of Q. ilex.

Metabolic responses of Quercus ilex seedlings to wounding analysed with nuclear magnetic resonance profiling

The study shows the rapid metabolic response of Q. ilex in defending its leaves, based on a rapid increase in the production of quinic acid, quercitol and choline. The results also confirm the suitability of 1H NMR-based metabolomic profiling studies to detect global metabolome shifts after wounding stress in tree leaves, and therefore its suitability in ecometabolomic studies.