Abstract Detail

Phytochemistry: From atoms to organisms

Salazar Amoretti, Diego [1], Valverde-Barrantes, Oscar [2], Sorich, Christopher [3].

Exploring the link between environmental gradients and secondary plant metabolites in the ancient plant clade Cycadales.

Plant specialized metabolites can play a central role in modulating species interactions. In the last 60 years, we have learned much about how specific specialized chemicals allow plant species to overcome or circumvent biotic and abiotic challenges. Still, plant chemical diversity remains an understudied component of the biological complexity of natural systems. Most notably, little is known about how these specialized metabolites vary across environmental gradients. Whether through the direct effect of environmental factors or indirectly through changes in the abundance and diversity of species interactions, environmental gradients are likely to be associated with significant variations in these specialized compounds' composition and concentration. Here we explore the patterns of variability of leaf specialized metabolites across the order Cycadales. In this phylogenetically controlled system, we specifically ask how large environmental gradients are associated with the interspecific variation in chemical composition and the concentration of some major secondary metabolite groups. We take advantage of an extensive outdoor living collection of cycads grown on a common garden set up to determine the leaf chemistry of a large percentage of all known cycad species. We used a combination of GCMS, HPLC-DAD/ELSD, and spectrophotometric assays to assess cycad leaf chemical composition. Despite the large phylogenetic scale of this study, we found a very high consistency in species secondary chemical composition across the order. This is especially evident across the interspecific variation in low molecular weight/volatile compounds (e.g.: mono-, sesqui-, triterpenoids, sterols, and short-chain fatty acids). Contrastingly, we found a high degree of variability in leaf phenolics. This variability is most apparent across flavonoids. Furthermore, taxa originating from sites with higher maximum annual temperatures showed significantly higher concentrations of flavonoids, especially for species originating in sites with maximum annual temperatures of 36 C. These results suggest that cycads are likely to rely on a small set of highly effective secondary metabolites and biosynthetic pathways to overcome the multitude of natural enemies across their large environmental and geographical range. This data also shows that environmental factors are also likely to play an important role in forging and modulating plant chemical diversity. We highlight the need for more comprehensive studies and experimental approaches to disentangle the direct and indirect effects of environmental factors on plant specialized chemicals.

1 - Florida International University, Biological Sciences, 11200 SW 8th Street, OE 167, Miami, FL, 33199, United States
2 - Florida International University, Biological Sciences, Biological Sciences, 11200 SW 8th Street, OE 167, Miami, Florida, 33199, USA
3 - 1610 Salzedo St. Apt 12, 1610 Salzedo St. Apt 12, Coral Gables, FL, 33134, United States

Keywords:
Cycads
Cycadales
secondary metabolites
Plant Chemistry
Environmental Gradients
phytochemistry
chemical defense  
Chemical Diversity.

Presentation Type: Colloquium Presentations
Session: C05, Phytochemistry: From Atoms to Organisms
Location: /
Date: Wednesday, July 21st, 2021
Time: 10:45 AM(EDT)
Number: C05003
Abstract ID:294
Candidate for Awards:None