A Metabolome Analysis and the Immunity of Phlomis purpurea against Phytophthora cinnamomi

Plants (Basel). 2023 May 9;12(10):1929. doi: 10.3390/plants12101929.

Abstract

Phlomis purpurea grows spontaneously in the southern Iberian Peninsula, namely in cork oak (Quercus suber) forests. In a previous transcriptome analysis, we reported on its immunity against Phytophthora cinnamomi. However, little is known about the involvement of secondary metabolites in the P. purpurea defense response. It is known, though, that root exudates are toxic to this pathogen. To understand the involvement of secondary metabolites in the defense of P. purpurea, a metabolome analysis was performed using the leaves and roots of plants challenged with the pathogen for over 72 h. The putatively identified compounds were constitutively produced. Alkaloids, fatty acids, flavonoids, glucosinolates, polyketides, prenol lipids, phenylpropanoids, sterols, and terpenoids were differentially produced in these leaves and roots along the experiment timescale. It must be emphasized that the constitutive production of taurine in leaves and its increase soon after challenging suggests its role in P. purpurea immunity against the stress imposed by the oomycete. The rapid increase in secondary metabolite production by this plant species accounts for a concerted action of multiple compounds and genes on the innate protection of Phlomis purpurea against Phytophthora cinnamomi. The combination of the metabolome with the transcriptome data previously disclosed confirms the mentioned innate immunity of this plant against a devastating pathogen. It suggests its potential as an antagonist in phytopathogens' biological control. Its application in green forestry/agriculture is therefore possible.

Keywords: Phlomis purpurea; Phytophthora cinnamomi; biotic stress; metabolomic and transcriptomic integration; plant immune response.

Grants and funding

This work was supported by the project PTDC/AGR-CFL/100217/2008, the D.N. grant SFRH/BD/66016/2009 and M.M. research contract 2022.07433.CEECIND, all funded by Fundação para a Ciência e Tecnologia (FCT). Fundação Calouste Gulbenkian provided financial support in the frame of the Academic Mobility Program for PhD Students, project reference number 122180. The APC charge was supported by the FCT’s UIDB/05183/2020 MED project. The founding agencies did not have any involvement in the design of the studies or in their analysis or interpretations.