Format: ORAL

Anglica Cibrin-Jaramillo1 and Francisco Barona-Gmez2,*

1 Naturalis Biodiversity Center, Leiden, the Netherlands 2 Institute of Biology, Leiden University, the Netherlands.

Cycads are known to host symbiotic cyanobacteria, including Nostocales species, as well as other sympatric bacterial taxa within their specialized coralloid roots. Even if it is reasonable to expect that Nitrogen-fixing microbiomes contribute towards the remarkable adaptability of cycads, it remains to be elucidated if (i) these bacteria share a phylogenetic origin and/or common genomic functions that allow them to engage in facultative symbiosis; (ii) how the metabolic products of these microbiomes mediate and sustain ‘symbiotic’ interactions amongst conserved bacteria and with the cycad host; and (iii) what is the role of these communities, and of the whole coralloid root, on cycad’s longevity, which remains to be determined. In this presentation, we will provide an integrated view on the cycad’s coralloid root, including its microbiome composition and related metabolic products, as well as the anatomy of the host itself, obtained after a broad range of analytical approaches. These include phylometagenomics and functional analysis of synthetic sub-communities, to evaluate evolutionary and functional relationships; metabolomics and imagining DESI mass spectrometry, to provide mechanistic insights underlying the symbiosis functions; and q-FISH to measure telomers lengths and laser ablation tomography to analyze internal anatomy of colonized and non-colonized coralloid roots. Results derived from our integrated approach support a role of coralloid roots on cycad’s adaptive resilience, central to the notion of developing cycads as an evolutionary plant model and with a bearing on conservation strategies of this highly endangered plant group.