Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species:Intraspecific dispersal of C4 physiology

Bianconi, M.E. and Dunning, L.T. and Curran, E.V. and Hidalgo, O. and Powell, R.F. and Mian, S. and Leitch, I.J. and Lundgren, M.R. and Manzi, S. and Vorontsova, M.S. and Besnard, G. and Osborne, C.P. and Olofsson, J.K. and Christin, P.-A. (2020) Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species:Intraspecific dispersal of C4 physiology. Proceedings of the Royal Society B: Biological Sciences, 287 (1938). ISSN 0962-8452

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Abstract

C 4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C 4 and non-C 4 populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C 4 lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C 4 phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C 4 physiology away from its region of origin.

Item Type:
Journal Article
Journal or Publication Title:
Proceedings of the Royal Society B: Biological Sciences
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2700
Subjects:
ID Code:
150475
Deposited By:
Deposited On:
12 Jan 2021 14:15
Refereed?:
Yes
Published?:
Published
Last Modified:
20 May 2021 15:48