Abstract Detail

Comparative Genomics/Transcriptomics

Munshi, Lamiaa [1], Christin, Pascal-Antoine [1].

Hybridization might have facilitated the rapid evolution of C4 photosynthesis in closely related Molluginaceae.

C4 photosynthesis is a trait that, despite its complexity, has evolved more than 60 times in angiosperms. C4 origins are especially clustered in some clades, a pattern that has been attributed to the recurrent co-option of anatomical precursors inherited from the common ancestor of these groups. The role of genetic precursors in the addition of a C4 biochemistry on top of these anatomical traits remains however debated. Here, we analyse the transcriptomes of various Molluginaceae species, including two C4 species that evolved from a C3-C4 intermediate common ancestor. We detect nine C4 genes that reach high levels in the C4 species, but these are low in the closely related C3-C4 intermediates. We conclude that C3-C4 species do not always bridge the gap to C4 biochemistry, and increased gene expression evolved independently in the two C4 Molluginaceae. We find evidence of shifts of selective pressures on the co-opted genes, but these are sustained in the descendant branches. These results show that the adaptation of C4 enzymes starts after their co-option but is then sustained over million of years. Finally, the phylogenetic trees of several of the co-opted genes are compatible with transfers among the C4 species after the divergence. We suggest that hybridization facilitated rapid C4 evolution in the group, with a role of the common C3-C4 ancestor limited to anatomical characters.

1 - the university of Sheffield, Animal and plant science, Western Bank, Sheffield S10 2TN, Sheffield, S10 2TN, UK

Keywords:
C4 photosynthesis
molecular evolution
Molluginaceae.

Presentation Type: Oral Paper
Session: CG1, Functional & Comparative Genetics/Genomics I
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 2:00 PM
Number: CG1007
Abstract ID:320
Candidate for Awards:None