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Pierre-Marc DELAUX

mail to pierre-marc.delaux
Tél : +33 (0)5 34 32 38 38

Equipe : Symbiose mycorhizienne et Signalisation cellulaire
Fonction : chargé de recherche CNRS


Origin, evolution and recruitment of the symbiotic pathways

The plant lineage faced two major transitions over the last 450 million years : the colonization of land and the transition from a gametophyte- to a sporophyte-dominant lifestyle, resulting in the divergence of vascular plants. These two events required the evolution of new mechanisms and the recruitment of existing pathways in a new developmental context. The fossil record and its broad host range suggest that Arbuscular mycorrhizal (AM) symbiosis evolved in the first Embryophytes (i.e. land plants) and was one of the critical innovations that allowed plants to successfully colonize lands. Interestingly, while new developmental features evolved, such as the roots in Lycophytes and Euphyllophytes, AM symbiosis has been maintained. Studying the evolution of AM symbiosis in land plants thus offers a unique opportunity to understand how key innovations evolved and were recruited during plant evolution.

Publications related to this topic

Delaux P-M.#, Radhakrishnan G., Jayaraman D., Cheema J., Malbreil M., Volkening JD., Sekimoto H., Nishiyama T., Melkonian M, Pokorny L., Rothfels CJ., Winter-Sederoff H., Stevenson DW., Surek B., Zhang Y., Sussman MR., Roux C., Morris RJ., Wong GKS., Oldroyd G., Ané J-M. The algal ancestor of land plants was pre-adapted for symbiosis. (2015) PNAS. 13390–13395 (doi : 10.1073/pnas.1515426112)

Delaux P-M., Séjalon-Delmas N., Bécard G., Ané J-M. Evolution of the plant–microbe symbiotic ’toolkit‘. (2013) Trends in Plant Science. 18:298-304 (doi : 10.1016/j.tplants.2013.01.008)

Delaux P-M., Xie X., Timme RE., Puech-Pages V., Lecompte E., Dunand C., Delwiche C.F., Yoneyama K., Bécard G., Séjalon-Delmas N. Origin of strigolactones in the green lineage. (2012) New Phytologist. 195 : 857-871 (doi : 10.1111/j.1469-8137.2012.04209.x.)

Convergent evolution : a way to discover new symbiotic genes

Homoplasy, or convergent evolution, refers to the independent emergence of a trait in species of different lineages. This independently evolved trait may arise from the recruitment of the same or different molecular pathways. Beside the convergent gain of traits, independent losses also occur. This is the case of the AM symbiosis in non-host lineages, such as the model angiosperm Arabidopsis thaliana. Interestingly, the independent losses of AM symbiosis are consistently correlated with the loss of a specific set of genes, including the well described symbiotic ones. These genes are top candidates for further reverse-genetic validations. Root nodule symbiosis formed in legumes and few other angiosperm species has been independently lost several times too. The sequencing of multiple genomes within these clades would provide the foundation to the discovery of genes related to root nodule symbiosis in an unbiased way.

Publications related to this topic

Delaux P-M.#, Radhakrishnan G., Oldroyd G.# Tracing the evolutionary path to nitrogen-fixing crops. (2015) Current Opinion in Plant Biology. (doi:10.1016/j.pbi.2015.06.003)

Delaux P-M.#, Varala K., Edger PP., Coruzzi GM., Pires JC., and Ané J-M.#. Comparative Phylogenomics Uncovers the Impact of Microbial Symbionts on Host Genome evolution. (2014) PLoS Genetics. 10:e1004487.

# corresponding author

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