Metabolite and transcript profiling of Guinea grass (Panicum maximum Jacq) response to elevated [CO2] and temperature

Authors: WEDOW, JESSICA - University Of Illinois; YENDREK, CRAIG - University Of Illinois; MELLO, TATHYANA - Universidad De Sao Paulo; CRESTE, SILVANA - Universidad De Sao Paulo; MARTINEZ, CARLOS - Universidad De Sao Paulo; Ainsworth, Elizabeth - Lisa

Submitted to: Metabolomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2019
Publication Date: 3/25/2019
Citation: Wedow, J.M., Yendrek, C.R., Mello, T.R., Creste, S., Martinez, C.A., Ainsworth, E.A. 2019. Metabolite and transcript profiling of Guinea grass (Panicum maximum Jacq) response to elevated [CO2] and temperature. Metabolomics. 15:51. https://doi.org/10.1007/s11306-019-1511-8.
DOI: https://doi.org/10.1007/s11306-019-1511-8

Interpretive Summary: In the coming decades, atmospheric carbon dioxide concentration is expected to increase by ~50% and global temperature is expected to warm by 2 ºC. These changes directly impact plant productivity. Scientists have used Free Air CO2 Enrichment (FACE) and infrared heaters to examine how plants will respond to rising atmospheric carbon dioxide concentration and temperatures, but most work has been done in temperate regions. This study investigated tropical Guinea grass response to global atmospheric change and rising temperature in the field in Brazil. Although warming treatments in temperate regions often decrease productivity, heating the canopy 1.5 °C above ambient in this experiment resulted in increased leaf area and biomass. Analysis of genes and biochemical metabolites identified pathways that were altered by growth at elevated [CO2] and temperature. Melibiose and xylose content were greater in plants exposed to elevated temperature, and content of these sugars was significantly correlated to the expression of genes involved in secondary metabolism, defense response and stomatal function. We hypothesize that the metabolite and transcript responses were associated with alleviation of stress and greater growth at elevated temperature. These results show that tropical C4 grasslands may have unpredicted responses to global climate change.

Technical Abstract: By mid-century, global atmospheric carbon dioxide concentration is predicted to reach 600 ppm with global temperatures rising by 2 ºC. Rising carbon dioxide concentration and temperature will alter the growth and productivity of major food and forage crops across the globe. Although the impact is expected to be greatest in tropical regions, the impact of climate-change has been poorly studied in those regions. This experiment aimed to understand the effects of elevated carbon dioxide concentration and warming, singly and in combination, on Panicum maximum Jacq. (Guinea grass) metabolite and transcript profiles. We created a de novo assembly of the Panicum maximum transcriptome. Leaf samples were taken at two time points in the Guinea grass growing season to analyze transcriptional and metabolite profiles in plants grown at ambient and elevated carbon dioxide concentration and temperature, and statistical analyses were used to integrate the data. Elevated temperature altered the content of amino acids and secondary metabolites. The transcriptome of Guinea grass shows a clear time point separations, with the changes in the elevated temperature and carbon dioxide concentration combination plots. Field transcriptomics and metabolomics revealed that elevated temperature and carbon dioxide concentration result in alterations in transcript and metabolite profiles associated with environmental response, secondary metabolism and stomatal function. These metabolic responses are consistent with greater growth and leaf area production under elevated temperature and carbon dioxide concentration. These results show that tropical C4 grasslands may have unpredicted responses to global climate change, and that warming during a cool growing season enhances growth and alleviates stress.