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PLANT GENOMICS

Fern genomes finally here

Nature Plants volume 4, pages 404–405 (2018)Cite this article

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The reference genomes of two fern species shed light on fern genome evolution and fern-cyanobacterial symbiosis, paving the way for understanding the unique and interesting biology of ferns.

In addition to providing the plant community with phylogenetically important genomic resources, Azolla is particularly noteworthy because it is home to an endosymbiont — the obligate, N2-fixing cyanobacterium, Nostoc azollae. As well as sequencing two fern genomes, Li et al. re-sequenced five other Azolla species and each of their endosymbiont Nostoc genomes, using these sequences to address questions regarding the Azolla–Nostoc symbiotic relationship. Is the common symbiosis pathway, or CSP, which is conserved in plants with arbuscular mycorrhizal (AM) and nitrogen-fixing root nodule (RN) associations, present in these ferns? Surprisingly, the answer is no. That genes homologous to six essential CSP genes are present in other ferns suggests that they were eliminated in the Azolla genomes. So, if not the CSP genes, what genes are essential for the association of Nostoc with its host? To identify such genes, Li et al. examined the differential expression of genes from Azolla grown in the presence or absence of either nitrogen or its cyanobiont. They found that the greatest changes in gene expression in response to nitrogen occurred when the cyanobiont was absent. Among the genes up-regulated in the absence of nitrogen but in the presence of the cyanobiont — a condition that would presumably promote nitrogen fixation by Nostoc — included ammonium and molybdate transporters and a chalcone synthase required for synthesis of the flavonoid narigenin (which promotes cyanobacterial growth). At this time, the greatest challenge to understanding the Azolla–Nostoc relationship will be to develop tools in Azolla to test the functions of these and other interesting candidate genes.

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Fig. 1: The floating water ferns Azolla filiculoides and Salvinia cucullata.

References

  1. Li. et al. Nat. Plants. https://doi.org/10.1038/s41477-018-0188-8 (2018).

    Article  Google Scholar 

  2. Shukla, A. K. et al. Nat. Biotechnol. 34, 1046–1051 (2016).

    Article  CAS  Google Scholar 

  3. Bateman, R. M. & Dimichele, W. A. Biol. Rev. 69, 345–417 (1994).

    Article  Google Scholar 

  4. Sussex, I. M. in Trends in Plant Morphogenesis (ed. Cutter, E.G.) pp 141–152 (Longman, London, 1996).

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  1. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA

    Jo Ann Banks

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  1. Jo Ann Banks
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Correspondence to Jo Ann Banks.

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Banks, J.A. Fern genomes finally here. Nature Plants 4, 404–405 (2018). https://doi.org/10.1038/s41477-018-0202-1

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  • DOI: https://doi.org/10.1038/s41477-018-0202-1

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